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Full text of "The principles of MEDLARS"

The principles of 

MEDLARS 



THE PRINCIPLES OF MEDLARS 



U.S. Department of Health, Education, and Welfare 
Public Health Service 
National Institutes of Health 
National Library of Medicine 
xVV 8600 Rockville Pike 
Bethesda, Maryland 20014 



For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402 - Price 75 cents 



z 

1976 

1.3 



INTRODUCTION 



The Medical Literature Analysis and Retrieval System (MEDLARS) is a 
mechanized bibliographic processing system which generates 
several different products and services, including: 

1. The monthly publication Index Medicus and the annual 
Cumulated Index Medicus . 

2. A number of published recurring bibliographies in 
specialized subject areas of medicine. 

3. Retrospective searches of the literature on particular 
topics conducted in response to specific requests made 
by members of the biomedical community. These are 
known as demand searches . 

4. Published literature searches on subjects of wide interest. 

All of these products are generated from the same input by a 
digital computer and peripheral eauipment. 

This handbook 

(a) describes MEDLARS in some detail, including its indexing 
procedures, vocabulary, searching strategies, products, 
and services; 

(b) indicates the types of requests that are suitable for 
retrospective machine search in MEDLARS; and 

(c) discusses the capabilities and limitations of the system. 

The purpose of the handbook is to further your understanding of 
MEDLARS and thereby assist you in making the best possible use 
of its services. 



Table of Contents 



The Coverage of MEDLARS 1 

Indexing for MEDLARS (Input Cycle) 1 

Processing the Citations 16 

Conducting the Demand Search 20 

Recurring Demand Searches 41 

Literature Searches 42 

Recurring Bibliographies 43 

Suitability of Requests for Processing 

as MEDLARS Demand Searches 45 

Factors Affecting Performance in MEDLARS 51 

Using the System Most Effectively 61 

Submitting Reouests 65 

Access to Articles Cited in MEDLARS Bibliographies 66 

Appendix A - Filling Out the Request Form 67-72 

Appendix B - National Library of Medicine Publications 73 

Appendix C - National Library of Medicine Recurring 

Bibliographies 74 

Appendix D - Availability of Interlibrary Loan and 

MEDLARS Search Services 75-77 



THE COVERAGE OF MEDLARS 



Approximately 18,000 separate journals are currently received at 
the National Library of Medicine. Of these, about 2,300 are indexed 
into MEDLARS. These 2,300 have been selected as an optimum set of 
biomedical journals in all languages, to satisfy the interests of 
the majority of MEDLARS users. An effort is made to maintain a 
reasonable balance between the various subject areas. 

In the selection of journals to be included in MEDLARS, the Library 
is advised by the Committee on Selection of Literature for MEDLARS, 
composed of leading physicians, medical librarians, and editors of 
medical journals. 

This committee constantly evaluates new journals being published 
for possible inclusion in Index Medicus. It also evaluates the 
status of journals already being indexed and considers suggestions 
about candidates for inclusion in the system. 

The List of Journals Indexed in Index Medicus (LJI) appears annually. 
It is published separately, but also appears in the annual Cumulated 
Index Medicus . In this list, the 2,300 titles indexed appear in 
four arrangements: by journal title, by journal- title abbreviation, 
by subject, and country of publication. A small additional group 
of unlisted journals, in special subject areas, are cited in MEDLARS 
products other than Index Medicus . 

Most journals are indexed cover-to-cover. Original articles are 
indexed, as well as those editorials, biographies, and obituaries that 
have substantive content. 

The designation selective is applied to those journals that are not 
exclusively medical. General scientific journals, such as Science 
and Nature, frequently contain biomedical articles. These journals 
are selectively indexed for their biomedical coverage only. 

INDEXING FOR MEDLARS (Input Cycle) 

As of March 1970 , the MEDLARS data base comprises over- one million 
citations to biomedical articles input to the January 1964 and 
subsequent issues of the monthly Index Medicus . This data base is 
now growing at the rate of about 200,000 citations annually. The 
great majority of the citations are to articles from journals and 
other serial publications (e.g., annual reviews), but some refer to 
the technical report literature. Approximately 50% of the articles cited 
are written in languages other than English. 



1 



The indexing process involves the careful analysis of articles and 
description of the contents of each by the use of specific subject 
headings selected from a controlled list. High-quality articles 
are indexed with as many terms (subject headings) as are needed to 
fully describe the subject matter discussed. Although there is no 
ceiling placed on the number of headings, in practice, between 
10 and 20 terms are assigned for these types of articles. They 
tend to be long, and are often research-oriented. 

Shorter articles, and those which contain less substantive 
information, are usually indexed with enough subject headings to 
describe the principal points or highlights of the article. 

The indexing is performed by a group of approximately 50 highly 
trained medical literature analysts, located at the National 
Library of Medicine and at MEDLARS Service Centers throughout the 
United States and abroad. 

Figure 1 depicts, side by side, completed indexer data forms for two 
journal articles, one of which required more subject headings than 
the other to describe its content. Any given citation is published 
in Index Medicus under only a limited number of the subject headings 
assigned to it. Such headings, which are known as print terms or 
Index Medicus terms (IM terms ) , are those which, in the indexer 's 
judgment, cover the principal points of the article. An X on the 
left of the data form under the IM column designates those TM terms 
under which the citation will be published in Index Medicus . The 
remaining headings assigned, non print terms or non Index Medicus 
terms ( NIM terms ), represent data or discussions, contained in the 
article, which are worth bringing out in the indexing but are not 
the central points of the article. All headings are recorded on 
the citation file (magnetic tape) and are used in machine search 
and retrieval operations. 



Experiences with stereotactic operations 
for Parkinson's disease 



rrai 



X STEREOTAXIC TECHNICS 
\RK1N50NISM' surgery 
HALAMUS • surgery 
MOVEMENT DISORDERS • diagnosis 
?ECH DISORDERS * diagnosis 



SPE 



TRLUOR 



STEREOTAXIC TECHNICS" mortality 
GAIT 
HEAT 
DSTURE 



Penicillin therapy of yaws 



(Spa) 



e5 



PENICILLIN * therapeutic use 
YAWS • drug therapy 
METHTCILLIN • therapeutic use 




Figure 1 



2 



Medical Subject Headings 



In describing the contents of an article, an analyst must use only 
those subject headings appearing in a list of accepted subject 
headings. This list, Medical Subject Headings , is published annually 
and i's generally referred to as MeSH. 

The published MeSH contains about 8,000 subject headings. All of the 
subject headings listed alphabetically in the first part of MeSH , 
(see figure 2) have been assigned to one or more of 14 broad subject 
categories, where semantically related terms are arranged in 
hierarchies in the categorized portion of MeSH . The 14 broad subject 
categories are as follows: 



A 


Anatomical Terms 


I 


Anthropology, Education, 


B 


Organisms 




Sociology, and Social Phenomena 


C 


Diseases 


J 


Technology, Industry and 


D 


Chemicals and Drugs 




Agriculture 


E 


Analytical, Diagnostic, 


K 


Humanities 




and Therapeutic Tech- 


L 


Communication, Library Science 




nics and Equipment 




and Documentation 


F 


Psychiatry and Psychology 


M 


Named Groups of Persons 


G 


Biological Sciences 


N 


Health Care 


H 


Physical Sciences 







These 14 categories are further subdivided into subcategories. For 
example, category C, Diseases, is subdivided into 17 subcategories, 
CI through CI 7 . 

The published MeSH contains about 9,000 cross-references to assist 
the user. These cross-references also appear in the annual Cumulated 
Index Medicus . There are four types: 

1. The see reference, which refers from a term not used to the 
appropriate synonymous or nearly synonymous term, as: 

Measles, German see RUBELLA 

2. The see under reference, which refers from a specific term 
not used to the most appropriate generic term, as: 

Median Palatine Cyst see under NONODONTOGENIC CYSTS 

3. The see also related reference, which links terms having 
closely related contexts (usually associating terms from 
different categories, such as an anatomical term and a 
disease term) as: 

MEDIAN NERVE see also related CARPAL TUNNEL SYNDROME 



3 



4. The see also specific reference, which links a generic term 
to one or more specific terms, as: 

MUSHROOMS see also specific PSILOCYBINE 

In addition, the printed MeSH contains reverse references to show 
terms referred from . For example, 

CARPAL TUNNEL SYNDROME XR MEDIAN NERVE 

which means that there is a see also related reference from MEDIAN 
NERVE to CARPAL TUNNEL SYNDROME. After each subject heading (also 
referred to as main heading) in MeSH appears the alphanumeric 
designation Tor the subcategory number (or numbers) to which the 
term belongs (see Figure 2). Thus, LIVER DISEASES is shown to 
belong to subcategory C4. Moving to C4 in the categorized section 
of MeSH , the analyst consults the term LIVER DISEASES and finds 
indented under it a list of specific liver diseases (Figure 3). 
Perhaps he will be able to find in this list a term that better 
describes the precise topic discussed in the article at hand, 
since the indexing rules reouire the analyst to describe each concept 
with the most specific term available in MeSH . If he selects 
HEPATITIS as the closest term available in this list, he can now 
look up this term, in the same subcategory, and find the terms 
that are subordinate to HEPATITIS (Figure 4). Perhaps he will 
make his final selection from this specific list. 

Subhead ings 

In addition to the approximately 8,000 subject headings, MEDLARS 
makes use of about 60 subheadings . Subheadings are general-concept 
terms which enrich the vocabulary considerably. They are used only 
in combination with main headings to show a particular attribute 
or effect of the concept expressed by the main heading. 

For example, a user of Index Medicus may want to locate articles on 
the liver, but from the anatomical point of view rather than that 
of physiology or metabolism. He does not need to look at all 
citations under LIVER but only at those under LIVER with the 
subheading "anatomy & histology." 



4 



LIVER (A3) 

LIVER ABSCESS (CI. C4) 

X ABSCESS. HEPATIC (CI. C4) 

LIVER ABSCESS, AMEBIC (Cl. C4) 
LIVER CIRCULATION (Gl) 

see also related 

HEPATIC ARTERY (A7) 
HEPATIC VEINS (A7) 
PORTAL SYSTEM (A7) 

XR HEPATIC ARTERY (A7) 
XR HEPATIC VEINS (A7) 
XR PORTAL SYSTEM (A7) 

LIVER CIRRHOSIS (C4) 

X CIRRHOSIS ICO 

X HEPATIC CIRRHOSIS IC«) 

XU CRUVEILHIER-BAUMGARTEN SYNDROME 
<C4> 

LIVER CIRRHOSIS. EXPERIMENTAL 

(C4) 

LIVER CIRRHOSIS. OBSTRUCTIVE 

(C4) 

X BILIARY CIRRHOSIS <C4) 

LIVER CIRRHOSIS, POSTNErROTIC 

(C4) 

LIVEP 



LOEFFLER'S SYNDROME (C5) 

X EOSINOPHILIC PNEUMONIA (C5) 
XR EOSINOPHIUA (C9) 



LOGIC (K) 

LONG-ACTING THYROID 
STIMULATOR (D12) 

X LATSID12) 



LONG TERM CARE (N2) 
LONGEVITY (Gl) 

see also related 

LIFE EXPECTANCY (Nl) 

LORDOSIS (C3) 

LORFAN see LEVA LLORPHAN I D6 
LORMIN see CHLORMADINONE { D2. D81 



LOVE (F) 



1 ^'ETH YLAMIDE 



Figure 2 



LIVER CIRRHOSIS, 

MENTAL 
LIVER CIRRHOSIS^ 

TIVE 
LIVER CIRRHOSIS^ 

NECROTIC 
LIVER DISEASES 
Acute Yellow Atrl 
Fatty Liver 
Hepa f ic Coma (Cl< 
Hepatic Vein Throi 

(C8) 
Hepatitis 
Hepatolenticular 



LIVER DISEASES (C4j 

LIVER DISEASES 

Acute Yellow Atrophy 
Fatty Liver 
Hepatic Coma 
Hepatic Vein Thrombosis 
Hepatitis 

Hepatolenticular Degeneration 

HEPATITIS 

Hepatitis, Animal 
Hepatitis, Homologous Serum 
Hepatitis, Infectious 
Hepatitis, Toxic 



Figure 4 



5 



The pairing of a main heading with one of its desired facets is 
called a main heading/subheading combination. For convenience, 
subheadings have been assigned to one or more MeSH categories, 
and explicitly defined. The analyst may pair any given main 
heading only with a subheading which is "allowable*' with the 
category to which the main heading belongs. Figure 5 shows 
a partial list of allowable combinations, and Figure 6 illustrates Q 
some correct and some incorrect combinations. 

It is correct to speak about the utilization of nursing homes, or 
drug effects on bone development. But it is incorrect to pair 
"adverse effects" with divorce, for example, even if it seems 
acceptable, because "adverse effects" has been defined to be 
used with drugs, chemicals, biological or physical agents, or 
diagnostic or therapeutic technics causing unintended or un- 
desirable reactions. The combination BONE DEVELOPMENT*chemically 
induced is incorrect because this subheading has been defined to 
mean that a disease has occurred as a result of using a drug. 

Some subheadings have wide applicability and may be used with 
terms from a number of different categories. Such a subheading 
is "metabolism." It is correct to speak of the matabolism of 
the pancreas (category A), the metabolism of Salmonella typhosa 
(category B) , metabolic aspects of pancreatitis (category C), or 
the metabolism of penicillin (category D). 

In-House MeSH 

The MEDLARS analysts have available to them a version of MeSH more 
complete and current than the version published annually. A 
specimen page is shown in Figure 7. This in-house MeSH is revised 
auarterly, and it contains about 1,000 more terms than the published 
MeSH . These additional terms are: 

1. geographical headings, and 

2. provisional headings. 

The geographical headings are used to describe articles with 
epidemiological, political, sociological, or geographic interest. 
For instance, consider articles on: 

Public Health in Ghana, 

The Occurrence of a Case of Yaws in New York City, 

The Cause of Illegal Abortions in Maryland, and 

Social Security or Disability Coverage of Neuroses in France. 

These articles are indexed under the most specific subject headings 
appropriate (PUBLIC HEALTH; YAWS; ABORTION, CRIMINAL; SOCIAL SECURITY) 
under which they will be found in Index Medicus . The appropriate ' 
geographic headings (GHANA; NEW YORK CITY; MARYLAND; FRANCE) are also 
indexed and stored for machine retrieval purposes. 



6 



Subheadings - 2 



INDEX MEDICUS SUBHEADINGS - 1970 
Alphabetical List of 60 Subheadings 



♦abnormalities (A) 
♦administration & dosage (D) 
♦adverse effects (D,E,H J) 
♦analysis (A,B,D,G,J)' 
♦anatomy & histology (A ,B) 
♦antagonists & inhibitors (D) 
♦biosynthesis (D) 
♦blood (C,D,F) 
♦blood supply (A) 
♦cerebrospinal fluid (C,D,F) 
♦chemical synthesis (D) ' 
♦chemically induced (C,l 
♦classification (B,C,DJ 

MpHraHn ^ (f ; Figure 



♦instrumentation (E,F,G,H,J) 
♦isolation & purification (b D) 
♦manpower (E,F,G,H,I,L,N) 
♦metabolism (A,B,C,D,F) 
♦microbiology (A,C) 
♦mortality (C,E,F) 
♦nursing (C,E,F) 
♦occurrence (C,F) 



MAIN HEADING 


- SUBHEADING 


COMBINATIONS 


VALID 


INVALID 


NURSING HOMES • 


FOOD- 


utilization 


adverse effects 


WATER SUPPLY • 


WATER- 


analysis 


supply & distribution 


BONE DEVELOPMENT • 


BONE DEVELOPMENT • 


drug effects 


chemically induced 



Figure 6 



XS PAPAVKR IB6) 

OPOSSUMS (B2) 

X DIDELPHIS (B2) 

OPPENHEIM-ZIEHEN DISEASE sec DYSTONIA 
MUSCULORUM DEFORMANS <C3, CIO) 

OPPKNHEIM'S DISEASE see AMYOTONIA 

CONGENITA (C3, CIO) 

OPSONINS (1)10, 1)12) 

XR PHAGOCYTOSIS (Gi) 

OPTIC ATROPHY (CIO, Cll) 
OPTIC CHIASM (A8) 
OPTIC I.OBE (A8) 



Figure 7 



ORGABOLIN see ETHYLESTRENOL (D2, D8) 
ORGAMETRIL see LYNESTRENOL (D2, D8) 

. ORGAN OF CORTI (A8, A9) 

X CORTI'S ORGAN (A8, A9) 
X SPIRAL ORGAN (A8. A9) 

ORGAN PRESERVATION see under TISSUE 
PRESERVATION (E5) 

ORGAN SPECIFICITY (Gl) 
ORGAN WEIGHT (E5) 
IRGAf 




Provisional headings (shown underlined in the in-house MeSH) are 
terms available for indexing and machine searching which have not 
yet been approved as main headings for inclusion in Index Medicus. 
Whenever an analyst assigns a provisional heading, he may also 
assign an appropriate more general term under which the citation 
will be found in Index Medicus . For example, an analyst uses the 
provisional heading ACTINOSPECTACIN to describe an article on this 
specific drug. He also assigns the more generic term ANTIBIOTICS, 
ANTINEOPLASTIC, under which the citation will be printed in Index 
Med i cus . 

At present, there are approximately 600 provisional headings, 
which are periodically analyzed and evaluated in terms of volume of 
use. If used freauently enough they will become main headings. If 
little used, they are retained for further analysis or dropped as 
being superfluous. 

The Indexing Operation 

Every day, each MEDLARS analyst is assigned a pile of journals to 
be indexed. This assignment is in keeping with his experience or 
level of training, his language abilities, and his subject knowledge 
Most analysts are able to read at least one foreign tongue, and 
many are able to index literature in four or five languages. 

The high production demanded by MEDLARS (about 200,000 citations 
annually) precludes the possibility of an indexer reading every 
word of an article. With practice, one can index efficiently 
without the perusal of every single word of a text. 

Analysts use a read/scan method based on the following instructions: 

1. Read and understand the title. 

2. Read the text down to the point at which the author states 
the purpose of his paper. 

3. Scan the text, reading chapter headings, section headings, 
bold-face, italics, charts, plates, X-rays, etc. 

4. Read every word of the summary. 

5. Closely scan the abstract. 

6. Scan the bibliographic references. 

This stage of the indexing operation is the stage of conce ptual 
analysis or content analysis (i.e. , deciding what the article is 
about) . 

The next stage involves the transformation of this conceptual 
analysis into the most appropriate set of subject headings and 
subheadings, which are then recorded on the indexer 's data form 
This form is the official worksheet of the analyst. A data form 
accompanies each article indexed in each journal from the point of 
indexing until the indexed citation has been input to the computer 



8 



A blank data form is shown in Figure 8. The upper portion is 
used to record a full bibliographic description of the article, 
and this forms the basis of the printed citation in Index Medicus 
or in a MEDLARS search printout. Some of the items-- for example, 
author's name and title of the article—are picked up by the input 
typist from the article itself, whenever these items appear in 
standard form. Other items of data--for example, translation and 
transliteration of foreign titles--are always supplied on the data 
form by the analyst or by an indexing clerk. The language of a 
foreign article is always indicated. This appears as an abbreviation 
in Index Medicus and can be used as a search parameter in retrieval 
operations . 

Check- Tags 

Before describing the contents of the article in MeSH terms, the 
analyst turns his attention to a set of routine items that must be 
accounted for in the indexing of every article. These items are 
known as check- tags , and they are preprinted on the data form so 
that the analyst can check off all appropriate terms. 

The analyst must account for the age of any person discussed in the 
article. He must also account for any experimental animals discussed. 
The names of the most common of these are preprinted for check-off. 
If a less common animal is involved, the analyst must select and 
record, elsewhere on the form, the most appropriate term from MeSH . 

Any historical note in an article must also be accounted for by 
checking the appropriate period check-tag. These historical items 
must be indexed under the most appropriate main subject heading, 
with the subheading "history" added. A geographical term should 
also be used where appropriate, and the check- tags are used to 
identify the article as being an historical article (historical 
note on a subject ) or an historical biography (historical note on 
a person ) . Biographical notes on living persons or persons 
immediately deceased are identified by checking the tag current 
biog-obit . 

All articles must be checked to indicate whether the study is 
performed on humans or on animals. In vitro studies must be 
identified. So must the sex of the person or experimental animal. 
The tag case report is used for an article that is simply a single 
case study. 

Studies describing controlled clinical research on human beings are 
identified by the check-tag clinical research , while studies of the 
comparative effects of two or more drugs, or two or more procedures 
or technics, are identified by the tag comparative study . 



9 



PAGINATION 



D • nan-std. do»» 

P • noo-tld. pog>not<On 
«UTHO» OA T A (pnnO 



author data Co 



TITLE (Entllth or Fnelt''' Trmn tlmllon) 



OPT PAGINATION 



TITLE (Vmrnmculmr or Trmnahrtrmred Vrmmculmr) 







MAIN HEADING •iubh«odin 9 


"rTo~ 


ENTRY VOCABULARY 






REVIE* References' 










ENGLISH ABSTRACT 


2 










9 








4 








s 








e 










7 






• 








I 








to 








1 1 








12 








13 








1 4 








1 5 








ie 








1 7 


INPUT TYPIST: DISREGARD TERMS BELOW 






1 t 








ta 








20 








2 1 








22 








2 ) 








24 














29 




IM 


NIM 


CHECK TAGS 


NIM 


CHECK TAGS 


NIM 


CHECK TAGS 


NIM 


CHECK TAGS 






PREGNANCY 




Cats 




HISTORICAL BIOGRAPHY 




CURRENT BIOG-OBIT 




INFANT, NEWBORN do 1 month) 




Cattle 




HISTORICAL ARTICLE 




ANIMAL EXPERIMENTS 






INFANT (1-23 months) 




Chick Embryo 




ANCIENT 




HUMAN 






CHILD, PRESCHOOL (2-5 years) 




.Dogs 




MEDIEVAL 




MALE 






CHILD (6-12 /ears) 




Frogs 




MODERN 




FEMALE 






ADOLESCENCE (13-18 years) 




Guinea Pigs 




15th CENT. 




IN VITRO 






ADULT (19-44 years) 




Hamsters 




16th CENT. 




CASE REPORT 






MIDDLE AGE (4S-64 years) 




Mica 




17th CENT. 




CLINICAL RESEARCH 






AGED (65- years) 




Monkey s 




18th CENT. 




COMPARATIVE STUDY 










Rabbits 




19th CENT. citati 


NO 












Rats 




20th CENT. 





DATA FORM - INDEX MEDICUS 



Figure 8 



10 



Four more items must be accounted for. Any well-documented survey 

of the recent literature on a specific subject is checked as review . 

The analyst also supplies the exact number of references. Review articles 

appear under their appropriate specific subject headings in Index Medicus 

and the Cumulated Index Medicus . They are also brought together 

in the review sections of these publications and are published 

separately as the Monthly Bibliography of Medical Reviews . 

The terms PREGNANCY and INFANT, NEWBORN must be checked whenever an 
article discusses a pregnant human or pregnant animal, or when a 
newborn infant is discussed. The citation to an article on normal 
pregnancy or the normal newborn infant must be printed under the 
heading PREGNANCY or INFANT, NEWBORN in Index Medicus . If the article 
deals with complications of pregnancy or diseases of the newborn, the 
headings PREGNANCY or INFANT, NEWBORN are used for storage in the 
computer. For Index Medicus , the indexer also assigns the headings 
PREGNANCY COMPLICATIONS or INFANT, NEWBORN, DISEASES. 

Coordinate Indexing 

The remaining space on the data form is reserved for the description 
of the article in terms of Medical Subject Headings . The analyst 
types all of the headings, with subheadings whenever appropriate, 
necessary to describe the content of the article. 

MEDLARS indexing is coordinate indexing . This means that complex 
concepts may be expressed by combinations or coordinations of two or 
more terms. We have already seen how we can combine a main heading 
with a subheading to express a more complex (specific) concept, 
as HEPATITIS*prevention & control. We can also express a complex 
concept by the joint use of two or more main headings. For example, 
an article discussing "community health services under Regional Medical 
Programs" would be indexed with the main headings COMMUNITY HEALTH 
SERVICES and REGIONAL MEDICAL PROGRAMS, both to be printed in Index 
Medicus . 

An article on "statistics on nursing homes" would be also indexed 
with two main headings: NURSING HOMES and STATISTICS. This citation 
would be found in Index Medicus under NURSING HOMES. STATISTICS would 
be stored for future machine retrieval of articles indexed under 
both NURSING HOMES and STATISTICS. 

Coordination may also be achieved by the joint use of a main heading 
and a check- tag. Thus, "hepatitis in females" may be expressed by 
assigning the term HEPATITIS and checking the tag FEMALE. 



11 



Some coordination already exists in the characteristics of certain 
main headings themselves. Thus, LIVER GLYCOGEN represents a pre- 
coordination of the concept "liver" and the concept 'glycogen 
Likewise, DIABETES MELLITUS, JUVENILE is a pre-coordmation of the 
concept "diabetes mellitus" and the concept "child." 

A cardinal rule of indexing in MEDLARS is that a topic is always 
indexed under the most specific available term. An article on 
sunburn is indexed under SUNBURN and not under BURNS , an article 
on eye burns under EYE BURNS and not under BURNS. An article on 
friction burns, however, would be indexed under BURNS because no 
specific term for friction burns exists in MeSH . 

Indexing Revision 

The work of trainees and junior indexers is subjected to a checking 
operation conducted by a fully experienced indexer, known as a 
"reviser." The reviser rapidly scans the bibliographic description 
and then concentrates on the assigned subject headings, asking the 
following Questions : 

Do the main headings reflect the true content of the article? 

Do the Index Medicus ( print ) headings cover the central points 
of the article? 

Are the headings spelled correctly, in exactly the form 
appearing in MeSH ? 

Are the correct subheadings used? 

Are all necessary check- tags present and have they been used 
correctly? 

Are the relationships expressed correct? Did disease X lead 
to Y or did Y cause X? 

Are the headings at the correct level of specificity for the 
article? 

The Analyst's Reference Tools 

The MEDLARS indexer is taught that the world's best authority for 
his indexing of an article is the text of the article itself. Beyond 
the article, however, he makes use of a number of basic tools and 
references . 

In addition to MeSH, the analyst has on his desk a copy of the 
Indexin S Manual. This is a 500- page volume of indexing policy and 
indexing interpretation revised, by monthly interim supplements, to 
conform with additions and changes in MeSH itself 



12 



The Integrated Authority File , a sample of which appears in Figure 
9, is a large MEDLARS entry vocabulary. It contains medical terms and 
expressions and foreign words and phrases occurring in the literature, 
showing how each should be indexed using the controlled vocabulary of 
Medical Subject Headings . It also includes provisional headings and 
scope notes that show how MeSH terms are defined and applied. 

Senior indexers have prepared various other compilations of indexing 
instructions relating to particular subject areas, such as respiration 
physiology, genetics, and steroids. 

The official dictionary used by MEDLARS analysts is Dorland 's Medical 
Dictionary . In indexing tumors, however, the indexer routinely 
checks each term used by an author against the American Cancer 
Society's Manual of Tumor Nomenclature and Coding . Standard 
texts on bacteria, viruses, enzymes, rheumatic diseases, hematology, 
cardiology, ophthalmology, and other subjects are available to the 
MEDLARS analyst for instant reference. For example, he uses the 
Index Bergeyana for bacteria and Andrews' Viruses of Vertebrates 
for viruses. 



BERTIELLA 



49 



blgarrure 



BERTIELLA (Bl) 1967 

genus under Cestoda; tapeworms found 
in primates and occasionally in 
domestic animals and man (MeSH 
def init ion) 



beutacultura (It) 

csubmerged cultures j 
Index CULTURE MEDIA (68) 

Bewegungsbestrahlung 

e moving-beam irradiation j 



bertlelllasls 

Index CESTODE INFECTIONS (IM) (68) 
BERTIELLA (IM) (68) 

Bertolotti's syndrome 

(Ruhl & Sokoloff: A Thesaurus of 

Rheumatology) 

Index SCIATICA (IM) (68) 

SPINAL DISEASES (IM) (68) 

BESNOITIASIS (C1.C15) 1968 
syn. globldiosis 

infection with protozoa of the genus 
Besnoitia (Globidium) (MeSH definition) 



Bezold- Jarisch reflex 

respiratory arrest, bradycardia and 

lowering of blood pressure 

Index RESPIRATORY INSUFFICIENCY (IM)(68) 
BRADYCARDIA (IM) (68) 
BLOOD PRESSURE (IM) (68) 



BF1 virus 

virus isolated from bovine feces which 
is cy topathogenic for tissue culture 
cells (C R Soc Biol (Par) 153:1653 
1959) 

Index VERTEBRATE VIRUSES (68) 



Bessau's nutrient 

an infant nutrient facilitating the 
growth of intestinal Lactobacillus 
bifidus flora (Gyermekgyogyaszat 
9:299 Oct-Nov 58) 
Index LACTOBACILLUS *growth & 

developement (IM) (68) 
INTESTINES *microbiology (IM) (68) 



BGA virus 

blue-green algae virus (J Bact 88:771, 
Sep 64) 

Index PLANT VIRUSES (IM) (68) 
ALGAE (NIM) (68) 




Figure 9 



13 



An Example of the Indexing Procedure 



To illustrate the MEDLARS indexing process further, it may be 
useful to look over the shoulder of an indexer, as it were, to 
see the steps involved in sub jec t- indexing a typical article. 
The sample article is entitled "Positive Sputum Cytologic Tests 
for Five Years Before Specific Detection of Bronchial Carcinoma. 

After reading key portions of the article, and scanning the 
remaining text, the indexer decides that the article deals 
primarily with the diagnosis of pulmonary and bronchial neo- 
plasms by means of cytological tests of the sputum. He therefore 
assigns the following main heading/subheading combinations: 



X SPUTUM*cytology 

X CARCINOMA, BRONCHOGENI C *d i a gnos i s 

X BRONCHIAL NEOPLASMS*diagnosis 

X LUNG NEOPLASMS -diagnosis 

indicating by the X that these are print terms, representing 
headings under which the citation should be printed in Index 
Medicus. This is also a study, by cytological methods, of the 
pathology of various types of tumors, and this leads him to 
assign the additional terms: 



BRONCHIAL NEOPLASMS*pa thology 
CARCINOMA, EPIDERMOID*pa thology 
CARCINOMA, BRONCHOGENI C*pa thology 
ADENOCARCINOMA*pa thology 
CYTODIAGNOSIS 



The patient discussed in the article, a 72-year-old man, was 
subjected to various diagnostic procedures, including radiography, 
bronchoscopy, and biopsy. The following terms were therefore 
assigned : 



BRONCHIAL NEOPLASMS*rad iography 
CARCINOMA, BRONCHOGENIC*rad iography 
BRONCHOSCOPY 
BIOPSY 



and the following check- tags were marked: 



AGED 

HUMAN 

MALE 



In addition, the provisional heading TIME FACTORS was assigned to 
account for the time period (five years) over which the cytologic 
tests were conducted. The completed data form is shown as Figure 



You have nov completed a broad outline course in MEDLARS indexing 
In a later section, you will learn how the results of this index? 
are used in the searching and retrieval of medical literatu 



ing 

re . 

14 



ARTICLES 



INDEXER 



A * anonymous 



D - non-std. date 



P - non-std. pagination 



PAGINATION 



318-24 



OPT. PAGINATION 



AUTHOR DATA (print) 



AUTHOR DATA (sort) 



TITLE (English or English Translation) 



TITLE (Vernacular or Transliterated Vernacular) 



IM 


N IM 


MAIN HEADING 'subheading 


NO. 


ENTRY VOCABULARY 






REVIEW ( References) 


1 








ENGLISH ABSTRACT 


2 








3 




X 


SPUTUM *cytology 


4 




X 


CARCINOMA. BRONCHOGENIC ^diagnosis 


5 






BRONCHIAL NEOPLASMS *radioeraphv 


6 




X 


BRONCHIAL NEOPLASMS *diaenosis 


7 






CARCINOMA. BRONCHOGENIC *radiographv 


8 






CYTODIAGNOSIS 


S 






BRONCHIAL NEOPLASMS *pathologv 


10 






BRONCHOSCOPY 


1 1 






CARCINOMA. EPIDERMOID *pathologv 


12 




X 


LUNG NEOPLASMS ^diagnosis 


1 3 






ADENOCARCINOMA *patholoev 


1 4 






CARCINOMA. BRONCHOGENIC *pathologv 


1 5 






BIOPSY 


16 








1 7 


INPUT TYPIST: DISREGARD TERMS BELOW 




TIME FACTORS 


1 • 








1 9 








20 








21 








22 








23 








24 










25 





CHECK TAGS 



NIM CHECK TAGS NIM 



CHECK TAGS 



CHECK TAGS 



PREGNANCY 



CATS 



HISTORICAL BIOGRAPHY 



CURRENT BIO-OBIT 



INFANT, NEWBORN (to 1 month) 



CATTLE 



HISTORICAL ARTICLE 



INFANT (1-23 months) 



CHICK EMBRYO 



ANCIENT 



AN IMAL EX PER I M EN T 
HUMAN 



CHILD, PRESCHOOL (2-5 years) 



DOGS 



MEDIEVAL 



MALE 



CHILD (6-12 years) 



FROGS 



MODERN 



FEMALE 



ADOLESCENCE (13-18 years) 



GUINEA PIGS 



ADULT (19-44 years) 



HAMSTERS 



1 5th C ENT. 
16th CENT. 



IN VITRO 



CASE REPORT 



MIDDLE AGE (45-64 years) 



MICE 



17th CENT. 



CLINICAL RESEARCH 



AGED (65- years) 



MONKEYS 



18th CENT. 



COMPARATIVE STUDY 



RABBITS 



19th CENT. 



CITATION NO. 



RATS 



20th CENT. 



NIH-1416 

REV. 3-69 



DATA FORM - INDEX MEDICUS 

FIGURE 10 15 



GPO 1969 0 — 350-778 



PROCESSING THE CITATIONS 



The monthly output of completed indexer data forms (about 
20,000 monthly in 1970) is used as input to procedures which 
generate the machine-readable data base. The subject headings 
assigned to a particular journal article, together with the 
full bibliographic citation for this article, are put into 
machine-readable form by input typists using paper tape type- 
writers. These machines simultaneously produce a punched 
paper tape and a proof paper copy. After proofreading, the 
input paper tapes and correction tapes go through a computer 
input procedure which transfers the input data for each article 
(bibliographic citation plus index terms) to magnetic tape. 
This cycle is depicted graphically in Figure 11. 




Figure 11 



Production of Index Medicus (Publication Cycle) 

The magnetic tapes produced by these input procedures contain 
unit records for each citation, arranged sequentially in order 
of accession (i.e., in citation-number order). For each citation 
the following data are recorded: citation number, author and 
title of article (including English translation of foreign titled 
journal reference, language abbreviation for languages other 
than English, all the subject headings assigned by the indexer 
and other pertinent information such as place of publication ' 
For review articles, the number of references is also recorded 
The contents of the tape are shown in simplified form in Figure 



12. 

16 



The magnetic tape containing one month's input of indexed citations 
is processed to generate the next monthly issue of Index Medicus. 
The computer programs used to generate this publication are 
rather complex (see Figure 13). Essentially, however, they 
accomplish the following tasks: 



CITATION 




NEXT 
CONSECUTIVE 
RECORD 



I 



BIBLIOGRAPHIC 
CITATION 



SMITH j R BASEMENT MEMBRANE 6001 
BIOLOGICAL TRANSPORT* 
FATS/METABOLISM* 

* 




ASSIGNED INDEX TERMS 



Figure 12 



1. Replication and Sorting . A citation is replicated and 
sorted under all the headings under which it is to be 
printed (i.e., all the headings marked as prin t headings 
by the indexer, plus author headings and cross-references 
for the author section.) 



2. Formatting . A series of programs transforms each citation 
into standard print formats, arranges the citations in the 
columnar form in which they will appear in the final 
publication, and handles such additional items as page 
headings, column headings, and page numbers. 



3. Photocomposing . The correctly formatted tapes are processed 
by a photocomposing machine known as GRACE (Graphic Arts 
Composing Equipment). The final product of GRACE is a roll 
of exposed paper, each roll containing about 120 pages for 
publication (Figure 13). 



17 




Figure 14 
18 



LIVER 



LIVER (A3) 

Liver scanning. Bennett LR, et al. 

Amer I Gastroent 50:355-65, Nov 68 
An Improved procedure for the preparation of Indium 
labeled lung and liver scanning compounds. Bruno FP, 
et al. Amer J Roentgen 104:762-5, Dec 68 
Rat liver phenylalanine tRNA: column purification and 
fluorescence studies. Fink LM, -et al. 
Blochem Btophys Res Commun 32:963-70, 30 Sep 68 
The role of the antlcodon region In homologous and 
heterologous charging of tRNA-Phe. Thlebe R, et al. 
Blochem Btophys Res Commun 33:260-5, 24 Oct 88 
Structural and functional aspects of rlbosome 
Interaction with endoplasmic reticulum membranes. 
Comorosan S, et al. Europ J Blochem 6:460-6, Nov 68 
Tc99m labelled toluldlne blue O for liver 

scintillography. Yeh SH, et al. 
[ Acidic glycosamlne glycans In the connective tissue of 
normal anrt <-irrhnti«- human liver) Delbruck A. 

(Oer) 




[Peritoneal tegumen of the liver and roots of the 
surface lymphatic bed In middle-aged and elderly 
persons) Boiko EG. Arkb Anat 53:39-46, Sep 67 (Rus) 

[Lymphatic vessels and segmental structure of the 
human liver) Volod'ko VP. 

Arkh Anat 52 65-79. Jan 67 (Rus) 
BLOOD SUPPLY 
[Functional variability of hepatic sinusoids In electron 



INDEX MEDICUS 



Bilirubin Inhibition of 4-methylumbelltferone glucuro 

conjugation In vitro by the human liver. Frezza M, et 

al. CUn Chlm Acta 21:509-12, Sep 68 
Effects of catecholamines and glucagon on amino acid 

transport In the liver. Chambers JW, et al. 

Endocrinology 83:1185-92, Dec 88 
Dally rhythms In the hydroxylatlon of 

3-beta-hydroxyandrost-5-en-17-one by rat liver 

microsomes. Colfrs A. et al. 

Endocrinology 84:165-7, Jan 89 
Changes In SH-estradlol distribution with development 

In the rat. Woolley DE, el al. 

Endocrinology 84:157-61, Jan 69 
Hepatic lnactlvatlon of renin In man. Kokot F, et al. 

Enzym Biol Clin (Basel) 9:317-9, 1968 
Effect of phenobarbltal on the conversion of 

cholesterol to taurocholtc acid. BUe acids and steroids 

204. Elnarsson K, et al. 

Europ J Blochem 6:293-8, Nov 68 
Formation and metabolism of 

cholest-5-ene-3beta,12alpha-dlol. BUe acids and 

steroids 205. Elnarsson K. 

Europ J Blochem 8:299-308, Nov 68 
Studies on the metabolism of C19-sterolds In rat liver. 3. 

Isolation and biosynthesis of 5alpha-androstanetrlols 

In rat liver microsomes. Gustafsson JA, et al. 

Europ J Blochem 6:317-24, Nov 68 
Arterial levels, cardiac and hepatic arteriovenous 

differences, extraction coefficients and oxygen 

extraction ratios of various substrates in normal, and 

In acute and chronic alloxan-dlabetlc dogs. Kraupp O, 

et al. Europ J Blochem 6:114-25, 17 Oct 68 
Biosynthesis of two new steroids In the human foetal 

liver, 1 beta- and 2 beta-hydroxytestosterone. Llsboa 

BP, et al. Europ J Blochem 6:419-24, Nov 68 
Formation of malonaldehyde from phospholipid 

arachldonate during microsomal lipid peroxidation. 

Nlehaus WG Jr, et al. 



and thiamine In various organs 
administration to rats. Itoka 
J vitamin (Kyoto) 14:134-41, 

Distribution of 35S in subcellul 
administration of thiamine 
(Inner). Itokawa Y, et al. 
1 Vitamin (Kyoto) 14:142-9, 

Cellular oxidation-reduction stac 
reactions In diabetic rat live 
coenzyme Q administration. 
1 Vitamin (Kyoto) 14:83-6, 

Mechanism of p-nltrobenzoate n 
possible role oc cytochrome 
microsomes. Gillette JR, et 
Molec Pharmacol 4:541-8, N< 

Fatty acid changes In liver fract 
lethal-dose radiation and thera 
Poult Set 47:1127-30, Jul 68 

Influence of carbon tetrachlor 
protein upon liver slice 
Blendermann EM, et al. 
Proc Soc Exp Biol Med 

18. Cellular adaptation In the dev 
to drugs. Axelrod J. 
Res Publ Ass Res Nerv Men 

[Level of reduced glutathlon ; 
activities during simple allox 
diabetes In mice] Le Cam 
Ann Biol Clin (Paris) 26:1213- 

[ Metabolic degradations of exo* 
at the level of the liver micros 
Ann Biol Clin (Paris) 26:1261 

[Test of the use of berylllun 
activity of the retlculoendott 
Vacher J. 
Ann Inst Pasteur (Paris) 115: 

[New data on the mechanlsn 
ervthrooolesls at the beglnn 



Figure 15 



The exposed paper is developed by an automatic processor. The 
developed paper is inspected, cut into page-size sheets, and 
packaged for delivery to a commercial printer. Offset printing 
and binding complete the publication cycle (Figure 14). Figure 
15 is a sample page from a monthly issue of Index Medicus. Note 
how the subheadings, as assigned by the indexers, are used to 
subdivide the entries under a main subject heading. After paper- 
tape input, all sorting, formatting, and composing functions are 
computer-controlled . 

Identical procedures are followed in the production of the annual 
Cumulated Index Medicus , although processing time for the annual 
publication is obviously much greater. 



19 



CONDUCTING THE DEMAND SEARCH 

Retrieval in MEDLARS, as in any other information system, is 
essentially a matching process. A request for literature on 
a particular topic is matched against the file of citations 
to biomedical articles that have been input to the system. 
When a match occurs, an article is retrieved. 

To facilitate the match between reouests and documents, both 
are described by means of terms selected from a controlled 
vocabulary, Medical Subject Headings ( MeSH ) . In the indexing 
operation, the subject matter of journal articles is described 
in MeSH terms. Similarly, a search formulation (search strategy) 
in MEDLARS is a description of an information requirement (as 
reflected in a request made to the system) in MeSH terms. The 
data processing capabilities of MEDLARS are used to match search 
formulations against the file of document descriptions (i.e., 
indexed citations). 

A simple example of a "retrieval" is presented in Table I. The 
requester is interested in the crossing of lipids through the 
placental barrier. A simplified search strategy for this request 
is given. This strategy states that an article should be 
retrieved only if it was indexed under the term MATERNAL- FETAL 
EXCHANGE and under a term indicating lipids. This formulation, 
when matched against the file of indexed articles, retrieves a 
citation to the article represented (along, presumably, with 
citations to other articles) which was indexed under MATERNAL- 
FETAL EXCHANGE and also under FATS, a term subordinate to LIPIDS 
in the MeSH vocabulary. 

The MEDLARS storage and retrieval operations are represented by 
a simple flow diagram in Figure 16. Note that the computer does 
nothing more than match search formulations against indexed 
citations. It has very little direct influence on the success 
or failure of a search. The degree of success of a MEDLARS 
search is determined largely by the intellectual efforts of 
MEDLARS analysts in indexing, searching, and vocabulary development 



20 



INPUT 



JOURNAL 
ARTICLES 




MEDICAL 
SUBJECT 
HEADINGS 



COMPUTER MATCHING 
OF 

SEARCH FORMULATIONS 
AGAINST INDEXED 
CITATIONS 



MEDICAL 
SUBJECT 
HEADINGS 



SUBJECT 
REQUESTS 



OUTPUT 



FIGURE 16 



Request Analysis 



A MEDLARS search request asks for the conduct of a retrospective 
search, through the indexed citations in the MEDLARS data base, in 
order to retrieve citations that deal with a particular item 
of subject matter. These requests are made by medical educators, 
practitioners, researchers, and other health professionals. 
Searches are requested for a variety of purposes: for example, 
to determine the state of research in a particular field, to 
assist in the preparation of a review article, or to help solve 
a clinical problem. Approximately 12,000 MEDLARS searches were 
completed in the United States in F.Y. 1969. 

In indexing an article for input to MEDLARS, the indexer goes 
through a two-stage process: 

1. deciding what the article is about, and 

2. describing the contents of the article by means of 
MeSH terms. 

A search analyst goes through the same two-stage process. First, 
he must decide what the request is about (i.e., what kinds of 
articles the requester really wants to see). Second, he must 
translate his interpretation of the request into a search state- 
ment, in MeSH terms, that can be processed against the citation 
file. 



In the analysis of a request, it is logical to begin by breaking 
the request into its various aspects, or facets. For example, 
consider a search for literature on the subject of renal amyloidosis. 
This request has two facets: (1) the organ facet (kidney) and 
(2) the disease facet (amyloidosis). The requester is not 
interested in all articles on the kidney, and he is not interested 
in all articles on amyloidosis. He is interested only in articles 
that discuss both facets of his request, i.e., kidney and amyloidosis, 
and which presumably deal with renal amyloidosis. This relationship 
between the two facets may conveniently be represented by a diagram 
of overlapping circles, as in Figure 17. 

I 







< 






^ *\ 1 




/ A 


^ B \ 


■ 


KIDNEY foj 


Km amyloidosis 



FIGURE 17 



22 



The rectangle I represents the entire MEDLARS collection. For 
this particular request we are interested in two classes of 
articles: the class (A) dealing with the kidney and the class 
(B) dealing with amyloidosis. Specifically, we are interested 
only in the intersection or overlap of these two classes, namely, 
the subclass AB that deals both with kidney and with amyloidosis. 
The overlap of classes is also known as the union , product , or 
intersection of these classes. The relationship between these 
classes is an AND relationship. In the above example, both 
classes must be present in order for an article to be of interest 
(i.e., KIDNEY and AMYLOIDOSIS). 

Having conceptually analyzed a reouest into its component facets, 

the next step involves translating this conceptual analysis into 

MeSH terms. There is no single MeSH term covering "renal amyloidosis." 

We must therefore search for articles that are indexed under terms 

indicating kidney and under terms indicating amyloidosis. We 

make use of MeSH to arrive at lists of terms indicating, on the 

one hand, kidney and, on the other, amyloidosis as follows: 



KIDNEY FACET 



AMYLOIDOSIS FACET 



MeSH Terms 
(selec tion 
only) 



KIDNEY 



or 



KIDNEY 

GLOMERULUS 

or 

KIDNEY 
PELVIS 

or 

KIDNEY 

. TUBULES 



and 



AMYLOIDOSIS 
or 
AMYLOID 



MeSH 
Terms 



Note that we will accept any of the selected terms indicating kidney 
and any term indicating amyloidosis. Thus, the terms in the kidney 
facet are all alternatives (substitutes) for one another The 
relationship between these terms i s therefore an OR relationshio 
We will accept KIDNEY or KIDNEY GLOMERULUS or KIDNEY PET VT^ or 
KIDNEY TUBULES. A list of alternative termini. e. terms in^n 
OR relationship) is called a sum of these terms. 



24 



Summations of classes can also be represented dia grammatically. 

In Figure 18, for example, we depict the sum of the class "amyloid" 

and the class "amyloidosis". Thus, in a MEDLARS search strategy, 



when we say AMYLOID £r AMYLOIDOSIS, we are specifying that we will 
accept any citation indexed under the term AMYLOID (Class A in 
Figure 18) or any citation indexed under AMYLOIDOSIS (Class B) 
or any citation indexed under both the term AMYLOID and the term 
AMYLOIDOSIS (AB) . 

A Simple Search Formulation 

Above we have graphically represented a very simple search 
formulation for a request on renal amyloidosis. By giving each 
term in this strategy a unique identifying number, and by using 
symbols that are recognized by the MEDLARS computer, we can reduce 
this strategy to a simple algebraic search equation. Consider 
the following: 

M 1 KIDNEY 

M 2 KIDNEY GLOMERULUS 
M 3 KIDNEY PELVIS 
M, KIDNEY TUBULES 

M Q AMYLOID 

o 

M 9 AMYLOIDOSIS 

In our search equation we want to specify that we will accept any 
article indexed under any one of the kidney terms, Mi - M 4 , and 
also under one of the amyloidosis terms, M 8 - M 9 . That is, we 
want the intersection or product of the class "kidney" and the 
class "amyloidosis" (Figure 17). This could be represented as 




FIGURE 18 



follows : 



(M x or M 2 or M 3 or M 4 ) and (M g or M g ) 



25 



However, in the search equation the OR relationship is represented 
by a plus (+) sign, while the AND relationship is represented 
by an asterisk (*) . We could therefore rewrite the above equation 
as follows: 

(M| + M 2 + M 3 + M 4 ) * (M 8 + M 9 ) 

In actual practice, we can compress this equation even further by 
assigning identifying numbers to sums of terms. Thus, we could 
say that M 5 - the sum of Mi through M4 (i.e., Ml or M 2 or M3 or M 4 ) 
and that M 10 = the sum of M 8 through M 9 . By adapting these further 
abbreviations, the whole search equation can now be reduced to 

(M 5 ) * (M 10 ) 

or. because (as we will explain later ) the parentheses now become 
redundant, to 



M * M 
n 5 10 

Using a very simple example, we have now gone through the entire 
search formulation process: 

1. Analysis of the reouest and identification of the 
facets involved. 



2. Selection of MeSH terms appropriate to each facet. 

3. Assignment of identifying numbers to the terms selected. 

4. Preparing summations of terms and a search equation that 
specifies which combinations of index terms must be present 
in order to cause a citation to be retrieved. 



Essentially, this is all that is involved in the process of search 
formulation. However, we have so far considered only one very easy 
example. Additional complexities are introduced in the next section. 

It is important to recognize that a search formulation is really 
a condensed statement of all the possible term combinations that 
could cause a citation to be retrieved. M5 * M-^q means that 
we will accept any citation indexed under a term represented by 
M5 (i.e., M x through M4) so long as a term represented by M 10 
(i.e., Ms through M9) is also present. In other words, going 
back to the terms selected above, we want to retrieve only those 
articles that have been indexed under one of the following term 
combina tions : 



26 



KIDNEY and AMYLOID 
KIDNEY and AMYLOIDOSIS 
KIDNEY GLOMERULUS and AMYLOID 
KIDNEY GLOMERULUS and AMYLOIDOSIS 
KIDNEY PELVIS and AMYLOID 
KIDNEY PELVIS and AMYLOIDOSIS 
KIDNEY TUBULES and AMYLOID 
KIDNEY TUBULES and AMYLOIDOSIS 



By assigning identifying numbers to each term, and by using the 
standard symbols, we have reduced this statement of acceptable 
term combinations to the very concise search equation M5 * M^q- 

It is also important to note that, in the above example, we 
have not placed any other restrictions on the citations that 
may be retrieved. That is, we will accept citations to any 
articles indexed under any of the term combinations listed 
above no matter what other terms have also been used in indexing, 
Thus, we are equally happy to retrieve any of the following 
articles : 



Only 
Two Terms 
Assigned 
In Indexing^ 



KIDNEY 
AMYLOIDOSIS 



Five 
Terms 
Assigned 



KIDNEY 
AMYLOIDOSIS 



Ten 
Terms 
Assigned 



KIDNEY 
AMYLOIDOSIS 



More Complex Requests 



Many of the requests made to MEDLARS are more complex than the simple 
two,- faceted request used as an illustration above. For example, 
the reouester might have asked for "renal amyloidosis as a 
complication of tuberculosis" or for the effect of prednisone on 
this condition. The former reauest is three- faceted , while the 
latter involves four facets: kidney, amyloidosis, tuberculosis, 
and drug therapy (specifically, prednisone therapy). These 
reauests are represented diagrammatically in Figure 19 and Figure 20. 



KIDNEY 



KIDNEY 
PREDNISONE 




AMYLOIDOSIS 



TUBERCULOSIS 



AMYLOIDOSIS 



TUBERCULOSIS 



FIGURE 19 



FIGURE 20 



27 



In the former case we are looking for the intersection of three 
classes. That is, we are seeking articles indexed under a kidney 
term and an amyloidosis term and a tuberculosis term. In the 
latter, we are demanding a fourth intersection: in addition 
to the above, a term indicating prednisone therapy must also be 
present . 

As the requests get more precise, and we demand that more terms 
must co-occur in order to cause retrieval, the volume of literature 
retrieved will become less. Thus, we expect more citations to be 
retrieved for a search on "renal amyloidosis" than we do for a ^ 
search on "renal amyloidosis as a complication of tuberculosis", 
and we expect more on the latter topic than we do on "effect of 
prednisone in cases of renal amyloidosis complicating tuberculosis." 

However complex the reauest, we can still reduce it to the type 
of search equation illustrated earlier. For example, the 
search equation 

M 5 * M 1Q * M 20 * M 25 

might be used to express the most complex request mentioned, where 
M5 represents a list ( sum ) of the kidney terms, M10 the sum of the 
amyloidosis terms, M20 tne sum of the tuberculosis terms, and M25 
the term PREDNISONE. 

From our previous discussion of MEDLARS indexing we know that terms 
may be assigned to an article to describe aspects other than purely 
subject aspects. These parameters can also be incorporated in 
search strategies. For example, we can search for review articles 
on amyloidosis (Figure 21), for articles on amyloidosis written 
in French (Figure 22), or for articles on amyloidosis from a 
particular journal (Figure 23). 



iCS ■ REVIHI 



AMYLOIDOS^S^^^^^E^IJW FIGURE 21 




AMYLOIDOSIS ■ FRENCH FIGURE 22 




AMYLOIDOSfIS ■ THE tiANCET 



FIGURE 23 



28 



Use of Subheadings in Searching 



The subheadings, used in combination with main headings to achieve 
greater specificity, are an important tool to aid the searcher in 
obtaining improved precision of search. For example, consider the 
request of a clinician who is looking for any articles that discuss 
cases of amenorrhea following discontinuance of oral contraceptive 
therapy. This is a two- faceted request: amenorrhea and oral 
contraceptives. It may be reduced to appropriate term lists as 
follows : 



M x AMENORRHEA 
M 5 CONTRACEPTIVES, ORAL 
M$ PROGESTATIONAL HORMONES 
My MEDROXYPROGESTERONE 
M g NORETHINDRONE 
Mq NORETHYNODREL 



However, if we and AMENORRHEA with the oral contraceptive terms, 
we may retrieve some unwanted citations on the use of oral contra- 
ceptives in the treatment of menstruation disorders. To avoid 
this, we can make use of the appropriate subheadings "adverse 
effects" and "chemically induced." We list these subheadings on 
our search formulation record and give them an appropriate code, as 

51 adverse effects 

52 chemically induced 

In our summation of the strategy we say: 

M 10 = SUM M 5 " M 9 
X 2 = M 1 /S 2 

The X element represents the combination of a main heading (or a sum 
of main headings) and a subheading (or a sum of subheadings). In this 
example, XI has been defined as the combination of every main heading 
included in the oral contraceptive facet and the subheading "adverse 
effects." X2 has been defined as the combination of AMENORRHEA with the 
subheading "chemically induced." 



^ Partial List of 

Appropriate Terms Only 



29 



We can now reduce the entire strategy to the simple search equation: 

Xi * X 2 

which means that we will accept for retrieval any citation indexed 
under AMENORRHEA with the subheading "chemically induced as long 
as an oral contraceptive term, with the subheading "adverse effects, 
is also present. 

The Logical "OR" in Searching 

We have already mentioned that the logical or (sum) can be used to 
indicate terms that are accepted as equivalent (substitutable) for 
search purposes; e.g., AMYLOIDOSIS or AMYLOID. We can also use 
logical sums to incorporate alternative search strategies into a 
complete search formulation. Consider a request for literature on 
the effect of cortisone on the choroid or the retina. This is 
represented in Figure 24. Here we are interested in any articles 



CHOROID 

CORTISONE y\ FIGURE 24 



indexed under a term indicating cortisone and also a term indicating 
choroid or retina. We can reduce this to a simple strategy as follows: 

Mj_ CORTISONE 

M 4 CHOROID 

M 5 RETINA 

M x * (M 4 + M 5 ) 

That is, retrieve any citations indexed under the term CORTISONE 
and either the term CHOROID or the term RETINA. 

A search equation is an algebraic expression with the characteristics 
of any other algebraic expression. Thus, the terms inside the 
parentheses are governed by everything outside. That is, Ml * (M4 +M5) 
is equivalent to Ml * M4 + Ml * M5 , which would be another way of 
writing the same search equation. 

M X * (M4 + M 5 ) 

is not the same expression as 

M]_ * M 4 + M 5 




30 



which means anything indexed under Ml and M4 or anything indexed 
under M5 (alone). See Figure 25. Note that the or (+) has here 
introduced an alternative search expression. 




FIGURE 25 



The logical or is also made necessary by changes in MeSH terminology 
over time. For example, consider a request for articles on the 
treatment of Tinea capitis with antifungal antibiotics. Before 
1967, there was no specific MeSH term to cover antifungal anti- 
biotics. They were indexed under ANTIBIOTICS, and under FUNGICIDES. 
However, the specific term ANTIBIOTICS, ANTIFUNGAL was introduced 
in MeSH in 1967. To retrieve the 1966 and subsequent literature, 
we have to say: 



TINEA CAPITIS and ANTIBIOTICS and FUNGICIDES 



or 



TINEA CAPITIS and ANTIBIOTICS, ANTIFUNGAL 
This may be reduced to a single search equation: 



M x * (M 2 * M 3 + M 4 ) 

where Ml represents TINEA CAPITIS, M2 ANTIBIOTICS, M3 FUNGICIDES, 
and M4 ANTIBIOTICS, ANTIFUNGAL. 

The Logical "Not" in Searching 

In addition to using the logical and and the logical jor, we 
can also negate terms by use of the logical not . Consider a 
request for literature on the effect of cortisone on retinitis but 
not where the retina is detached (Figure 26). 




FIGURE 26 



31 



Here we are interested in any article indexed ^^f™^ 
under CORTISONE but not if also indexed under RETINAL DETACHMENT. 
That is, we specifically wish to exclude articles with ^term 
RETINAL DETACHMENT. The negation (not) is expresse y 
of a minus sign ( - ). In this case we are saying and not ( -) 
and the search equation can be derived as follows. 

Mj_ RETINA 

M 2 CORTISONE 

M 3 RETINAL DETACHMENT 

M x * M 2 * - M 3 

In certain other cases we may wish to say or not (+ -) rather 

than and not (* -). For example, a requester may want to 

retrieve studies of blood circulation in the choroid in humans only. 

The check-tag HUMAN is now routinely applied to all articles describing 

studies in humans. However, this check- tag was not always used in 

MEDLARS. To retrieve the earlier articles on humans only we have 

to go the roundabout way by negating animal terms. Thus, a strategy 

covering the entire data base for the above request will have to 

say BLOOD CIRCULATION (Ml) and CHOROID (M2) and HUMAN (M3) or 

BLOOD CIRCULATION and CHOROID and not animal terms (M4) . This 

may be reduced to the search equation 

M x * M 2 * (M 3 + - M4 ) 

which reads M^ and M 2 and (M3 or not M4 ) . 

Subsearches 

The MEDLARS search programs allow up to three subsearches of 
increasing specificity to be combined within a single search strategy. 
Consider again the request for literature on renal amyloidosis as 
a complication of tuberculosis and the effect of prednisone on this 
condition. Perhaps the requester indicates that he is generally 
interested in all renal amyloidosis, particularly when this is a 
complication of tuberculosis. His most particular interest is in 
the effects of prednisone on this condition. For this request we 
can create a three-tiered strategy of increasing specificity: 

4 all articles on renal amyloidosis 

5 renal amyloidosis as a complication of tuberculosis 

6 the effects of prednisone on this condition 

In MEDLARS the numbers 4-5-6 are used to indicate subsearches of 
increasing specificity within a complete search formulation. Re- 
duced to a search equation, this will appear as follows: 



32 



M5 terms indicating kidney 



M 10 te rms indicating amyloidosis 



M 15 terms indicating tuberculosis 



M 30 the term PREDNISONE 



4 



M 



5 



* M. 



10 



5 



M 



15 



6 



M. 



30 



What we are saying here is that the broad strategy will retrieve 
anything on renal amyloidosis. From this subset of retrieved 
citations, those indexed under a term indicating tuberculosis 
will be separated out, and from this second subset will be 
separated out any indexed under the term PREDNISONE. Suppose 
that 100 citations satisfy the broad search requirement (i.e., 
they are indexed under a kidney term and also a term for amyloidosis). 
Of these, 20 also have a tuberculosis term present, and of these, 
two have been indexed under the term PREDNISONE. A total of 100 ' 
citations will be retrieved by this strategy but, when these 
citations are printed out by the computer, those most specifically 
related to the requester's need (Section 6 of the bibliography) 
will appear first, followed by the next most closely related 
(Section 5), and finally by the residue of citations that satisfy 
the most general search requirement only, as follows: 

Section 6 2 citations 

Section 5 18 citations 

Section 4 80 citations 
for a total of 100 citations satisfying the search logic. 
Developing the Lists of Search Terms 

In discussing indexing, we pointed out that the most specific 
available term is always used to describe a concept. Thus, an 
article on sunburn is indexed under SUNBURN and one on eye burns 
under EYE BURNS rather than under the more generic term BURNS. 

In searching the MEDLARS file, then, for articles on burns (nonspecific) 
in children, the search analyst must search on each specific "burn" 
term in the vocabulary, each one anded with terms indicating children. 
Of course, the term BURNS itself would be searched to retrieve those 
general references in which no specific type of burn was mentioned 
and those in which a specific type of burn was mentioned but for which 

no precise MeSH term exists. These articles (e.g., on friction burns) 
would be indexed under the general heading BURNS. 



33 



In this case the searcher must find all of the MeSH terms, general 
and specific, under which topics of interest may have been indexed. 
To do this, several searching aids are used. First, of course, is 
the alphabetical sequence of terms in MeSH itself. This is the 
primary source used for determining whether or not a desired 
heading is in the vocabulary. The cross-references in MeSH lead 
the searcher to many of those headings which might be considered 
for searching. In this case (Figure 27), we find no cross-references 
under BURNS, but we do find four terms we will want to consider: 



BURNS 

BURNS, CHEMICAL 

BURNS, ELECTRIC 

BURNS, INHALATION 

The searcher may also go to the categorized lists of terms, 
mentioned in the discussion of indexing, which appear in the blue 
pages of Medical Subject Headings . 

A very important tool used by the searcher is a hierarchical 
classification of MeSH terms known as the Tree Structures . In 
this, each of the categories in MeSH has been classified in a 
hierarchical manner. In Figure 28 we see the MeSH tree covering burns. 

BRONCHOPNEUMONIA (C5) 

BRONCHOPULMONARY 
SEQUESTRATION (C16) 

BRONCHOSCOPY (El) 

BRONCHOSPIROMETRY (El) 

BRUCELLA (B3) 

BRUCELLA ABORTUS (B3) 

BRUCELLA VACCINE (D12) 

BRUCELLOSIS (Cl) 

X MALTA FEVER (Cl) 
X UNDULANT FEVER (Cl) 

BRUCELLOSIS, BOVINE (Cl, C15) 

X ABORTION. INFECTIOUS (Cl, C15) 
X BANG'S DISEASE (Cl. CIS) 
X INFECTIOUS ABORTION (Cl, CIS) 

BRUNNER'S GLANDS tee under DUODENUM (AS) 

BRUXISM (C4) 
BRYOZOA (Bl) 

BUCCA see CHEEK (Al) 

Bl CL1ZINE (D6) 

BUDD-CHLUU SYNDROME »ee HEPATIC VEIN 
THROMBOSIS (C4. Ct) 

BUDDHISM (K) 

BUDR tee BROMODEOXYURIDINE ID10) 

BUERGER'S DISEASE tee THROMBOANGITIS 
OBLITERANS < 8 



BURKITT'S LYMPHOMA (C2) 

X AFRICAN LYMPHOMA (C2) 

X BURKITT'S TUMOR <C2) 

X LYMPHOMA, BURKITT'S <C2) 

BURKITT'S TUMOR see BURKITT'S LYMPHOMA 

(C2) 

BURMA (Zl) 
I BURNS (C14)1 
| BURNS, CHEMICAL (C14)| 
| BURNS, ELECTRIC (CuTf 
| BURNS, INHALATION (C14)| 

BURSA OF FABRICIUS (A13) 

XR THYMUS GLAND («7) 

BURSA, SYNOVIAL (A2) 
BURSITIS (C3) 
BURUNDI (Zl) 
BUSULFAN (D4) 

X MYLERAN rD4i 

BUTACAINE (D6) 

X BUTYN (D6) 

BUTADIENE (D2) 
BUTANONES (D2) 

XU AMPHENONE B (D2) 



Figure 27 
34 



C14 - INJURY, POISONING AND IMMUNOLOGIC DISEASE 

INJURY, IMMUNE DISEASE, POISONING (NON MESH) (CONTINUED) 
WOUNDS AND INJURIES (CONTINUED) 



ARM INJURIES (CONTINUED) 



FOREARM INJURIES 


C14.88.8.1 




WRIST INJURIES 


C14.88.8.1 




ASPHYXIA 


C14.88.10. 




ATHLETIC INJURIES 


C14.88.11. 




BIRTH INJURY 


C14.88.12. 


C16.70.8. 


Bl'iiS *ND STINGS 


C14.88.13. 


C14.66.18. 


BLAST INJURY 


C14.88.14. 




BRAIN INJURY, ACUTE 


C 14.88. 16. 


C14.88.36.1 


BRAIN CONCUSSION 


C14.88.16.1 




EPILEPSY, TRAUMATIC C14.88.16.1 


C10.18.39.1 




fIC C14.88.16.1 


F.34.11.1 


BURNS 


C14.88.18. 




BURNS, CHEMICAL 


C14.88.18.1 




BURNS, ELECTRIC 


C 14.88. 18.1 


C14 88.24 1 


BURNS, INHALATION 


C14.88.18.1 




EYE BURNS 


C14.88.18.1 


C14.88.27.1 


SUNBURN 


C14.88.18.1 




1 ConTFSToNS 


C14.88.20. 




DISLOCATIONS 


C 14.88.22. 




HIP DISLOCATION 


C14.88.22.1 




SHOULDER DISLOCATION C14.88.22.1 




ELECTRIC INJURY 


C14.88.24. 




BURNS, ELECTRIC 


C14.88.24.1 


C14.88.18.1 


ESOPHAGEAL PERFORATION C14.88.26. 


C4.29.36. 


EYE INJURIES 


CI 4.88.27. 





Figure 28 



From this listing, the search analyst discovers two additional terms, 
SUNBURN and EYE BURNS, not found by use of the alphabetical MeSH. 
As shown in the tree, BURNS is more specific than WOUNDS AND INJURIES 
and is therefore indented under the latter term. Indented under 
BURNS are' the five specific burn terms. The classification number 
CiA «ft i« has been assigned to the term BURNS and also to all 
specific burn terms indented under it. C14 is the subcategory 
Injury, Poisoning and Immunologic Disease. C14.88 refers more 
specifically to Wounds and Injuries. 

The great advantage of the tree structure is that it minimizes the 
time needed by the search analyst to conduct comprehensive generic 
searches. In this instance, if the searcher wants to ^corporate 
all "burn" terms into his formulation, he does not need to make a 
complete list. He merely records the tree number C14.88.18 and 
indicates that a generic search (known in MEDLARS as an explosion ) 
is to be conducted on this class. This explosion will retrieve 
any citation indexed under BURNS and any citations indexed under 
the specific burn terms subordinated to BURNS in tte hierarchy. 



35 



The tree structures are even more useful as aids to searching on 
concepts for which a large number of specific terms exist in the 
vocabulary. Consider a search relating to the brain for example. 
All of the specific anatomical terms relating to the brain are 
shown subordinated to the term BRAIN in A8.30.13 (see Figure 29). 
The searcher may "explode" on A8.30.13 thereby retrieving citations 
indexed under any of the specific brain terms, or he may select 
those brain terms that are most appropriate to the particular search 
being conducted. It is important that the user indicate, in his 
request statement, any aspect in which he is not interested. In 
this instance, if he is not interested in, say, the frontal lobe, 
he should make this clear in his request. 

There are several other headings in MeSH which relate to the brain, 
and the searcher must at least consider these in building up his 
formulation. In order to find such terms, the searcher considers 
the following: 

1. Terms with "roots" indicating the brain (e.g., cerebro- 
encephalo-, cerebello-). 

2. "Function words" indicating brain involvement (e.g., 
the terms BLOOD-BRAIN BARRIER, THINKING, INTELLIGENCE). 



A8 - NERVOUS SYSTEM 



NERVOUS SYSTEM 

CENTRAL NERVOUS SYSTEM 
BRAIN 

AMYGDALOID BODY 
'AUDITORY CORTEX 
BRAIN STEM 
CEREBELLAR CORTEX 
CEREBELLO PONTILE ANGLE 
CEREBELLUM 
CEREBRAL CORTEX 
CEREBRAL VENTRICLES 
CHOROID PLEXUS 
CISTERNA MAGNA 
CORPORA QUADRIGEMINA 
CORPUS CALLOSUM 
'CRANIAL FOSSA, POSTERIOR 
DIENCEPHALON 
EPENDYMA 
FRONTAL LOBE 
GENICULATE BODIES 
GYRUS CINGUU 
HIPPOCAMPUS 

HYPOTHALAMO-HYPOPHYSEAL SYSTEM 
HYPOTHALAMUS 
LIMBIC SYSTEM 
MEDULLA OBLONGATA 
MESENCEPHALON 
OCCIPITAL LOBE 
OLIVARY NJ 
•OPTIC 
PARI! 

Figure 



A8. 
A8.30. 
A8.30.13. 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A8.30.13.1 
A*. 



A8.45.S2.1 
Gl. 77.48. 1 



A8 30 28 1 



A2.84 49 1 



A8.6013 A10.9918. 



A8.54 45 1 G1 45.25 Gl.77.22. 



29 



36 



3 * ENCEP^OrRAPHV 8 ^n"" 8 t0 brain > Such as ELECTRO- 
ENCEPHALOGRAPHY and CEREBRAL ANGIOGRAPHY. 

4. Terms indicating pathological conditions (i.e. BRAIN 

DISEASES). ^.e.,BKAlN 

5. Terms that may indicate surgical procedures on the brain 
(e.g., CRANIOTOMY). 

111 f^ 1 ^ the se *rcher must remember to take into account changes 
m the MeSH vocabulary over the years. For example if he is 
searching the 1964-1965 citations, he must use the pre-coordinated 
term BRAIN PHYSIOLOGY. For later material he must search on the 
main heading/subheading combination BRAIN/ phys io logy . In January 
1966, subheadings were introduced in MEDLARS. As a result, a 
large number of precoordinated terms such as BRAIN PHYSIOLOGY 
which had existed in the vocabulary were de-coordinated to allow 
for the use of the subheadings. The searcher has tools available 
to show the evolutionary changes in MeSH terms and also definitions 
of the scope of these terms. 

A further important tool (see Figure 30) is a computer printout of 
all the main headings and the number of times each has been used 
in indexing. This number (the tally ) is very important to the 
searcher, for it allows him to make a rough estimate of the number 
of citations likely to be retrieved by a particular strategy. 



EMBOLISM, FAT (C8J, C8.78.32.1 ^ 233 

1558 



EMBRYO (A10) ^^BHl A10.22 

CELL DIFFERENTIATION (G1) 

EMBRYOLOGY (G1) G1.10.48 1100 

EMBRYOTOMY (E4) E4.73.32.1 8 

EMERGENCIES (C17) C17.21.40 674 

FIRST AID (E2) 

HOSPITAL EMERGENCY SERVICE (N2) 

EMERGENCY HEALTH SERVICES -HH N2.72.23 fe> 47 



(N2) ^ 

FIRST AID (E2) 

XR CIVIL DEFENSE (G3) 
EMETICS (D6) D6.75 46 

XR ANTIDOTES (D13) 

XR VOMITING (C4, CI 7) 
EMETINE (D2, D3) 

Figure 30 



37 



An additional printout shows the number of times a given subheading 
has been used with a main heading. 

The Demand Search Formulation Record (DSFR ) 

All possible relations between classes of documents (and, thus, the 
subject headings representing these classes) may be expressed in 
terms of logical sums (ors ) , logical products (ands ) , and logical 
differences ( nots or negations ). When reduced to a search equation, 
these relationships are expressed by +, *, and - . For purposes 
of illustration, we have drawn our examples from fairly simple 
requests involving relatively straightforward strategies. However, 
complex requests, involving many more terms, may be reduced to search 
equations in the same way. 

The search analyst prepares his strategy on a special form known as 
the Demand Search Formulation Record (DSFR). An example is shown 
in Figure 31. This particular request is for articles on tissue 
culture studies of human breast cancer. It has three facets: 



1. Breast Cancer 

2 . Human 

3. Tissue Culture 



Note how the searcher has divided up his list of terms into separate 
lists for each facet. The breast cancer terms are two: BREAST 
NEOPLASMS and CARCINOMA, DUCTAL. To arrive at the requirement for 
"human," he searches on the term HUMAN and also negates terms in- 
dicating animal studies, including the subheading VETERINARY. There 
are three tissue culture terms to be searched. Finally, he indicates 
that the search is to be conducted on English- language material only. 

Having decided on his search terms, the searcher gives them identifying 
numbers with the prefix M for main subject headings, S for subheadings, 
and L for language. He wants to negate all vertebrate terms and all 
animal disease terms so he lists the category numbers (B2 and C15) and 
indicates by use of the e in column 17 that these terms are to be 
exploded. In the central portion of the form he records his summations: 
M3 for the two breast cancer terms, M16 for the four animal terms, 
and M23 for the three tissue culture terms. Finally, he reduces the 
entire strategy to a search equation ("request statement"): 

M 3 * (M 1Q + - M 16 * - S X ) * M 23 * L X 



38 



REQUEST NO 



DEMAND SEARCH FORMULATION RECORD 



2 Aug 1969 



Tissue culture studies of human breast cancer. 



19-31 



Ml 



M2 



MIO 
Mil 
M12 
Ml? 

mk 



M20 
M21 
M22 



LI 
SI 



P2 



CI 5 



ELEMENTS 



BREAST NEOPLASMS 



CARCINOMA, DUCTAL 



HUMAN 

VERTEBRATES 
ANIMAL EXPERIMENTS 
VETERINARY MEDICINE 
ANIMAL DISEASES 



TISSUE CULTURE 
CULTURE MEDIA 
CHICK EMBRYO 



ENG 

Veterinpry 



ui>- w 

H il CD 



ELEMENTS 



E L EM. 
S YM80L 



ELEMENTS A, J, I, N, Y, X, AND SUMMATIONS 



33-36 



M3 

Ml6 

M2-5 



SUM 
SUM 
SUM 



37-40 



Ml 

Mil 
M20 



41-44 



M2 

Mil* 
M22 



ELEM. 
SYMBOL 



REQUEST STATEMENTS 



11-80 COLUMNS 



M^ * ( MIO + -Ml 6 * -ST ) * M23 * LI. 



1 1 



BATCH NO. 


OS MODULE 


COM M E N TS 


RG MODULE 


COMMENTS 























PHS-4667-2 (4-67) 



Figure 31 
39 



which translates as 



BREAST NEOPLASMS 
or 

CARCINOMA, DUCTAL 



and 



HUMAN 

or not 

any term 
indicating 
animal or 
animal 
disease 

and not 

the 
subheading 
"ve terinary" 



and 



TISSUE 
CULTURE 

or 

CULTURE 
MEDIA 

or 

CHICK 
EMBRYO 



and ENGLISH 



No subsearches of increasing specificity were used in this particular 

strategy because the total volume of retrieval was expected to be 

low. In actual fact, only 11 citations were found to meet the search 
requirements . 



The Machine Search and Its Output 

Once the search strategy has been reduced to an appropriate search 
equation, the entire formulation -- terms and search equation -- 
are put into machine-readable form by the use of punched cards. The 
search is now ready for processing. Several searches are batched 
together and processed simultaneously, as illustrated earlier in 
Figure 16. The search formulation is matched sequentially against 
the complete data base of indexed citations. A citation is retrieved 
from this data base when its index terms match one of the combinations 
of index terms demanded by the search strategy. Qualifying citations 
are copied from the main citation file onto a retrieved citation tape . 
Before the retrieved citations are printed, however, printing instructions 
are supplied by the search analyst who formulated the search. The 
following options are available: 



1. The citations may be printed on 3" x 5" cards or on continuous 
computer paper (8V x 11"). 

2. The citations may be arranged in a number of different ways, 
inc luding : 



a. alphabetically by first author, 

b. by journal title abbreviation, or 

c. by language. 



40 



Illustrations of partial search printouts in paper and card formats 
are included as Figs. 32 & 33. Notice that the citations contain -- in 
addition to the traditional bibliographic reference given in Index 
Medicus -- a listing of all the headings used in indexing the article. 
These terms may aid the user in deciding which articles he may 
want to read. 

The searcher's final responsibility is to carefully review the printout 
for probable success or failure and then to take appropriate action. 
If the retrieved citations appear to meet the requester's needs, the print- 
out is mailed to him with an explanatory letter. If, in the searcher's 
estimation, the search results are poor, he may try another approach 
and reformulate the search, or he may contact the requester and 
discuss the problem with him. Adequate interaction with the user 
prior to initial formulation, along with careful thought during the 
formulation process, will usually avoid the need for reformulation. 

RECURRING DEMAND SEARCHES 

Some Demand Searches (conducted mainly for Government organizations) 
are activated periodically (monthly, bimonthly) without the requester 
having to resubmit his request. These searches are used for a variety 
of purposes, such as training or keeping an up-to-date file of literature 
on a specific subject. 



ACKERMAN NB 

SCANNING AND IRRADIATION oF THE LIVER WITH RADIOISOTOPES, 
AHER J SURG 1121363-7* SEP 66 

HUMAN (4)* OLIVER DISEASES/ DIAGNOSIS* OLIVER DISEASES/ 
RADIOTHERAPY* LIVER NEOPLASMS/ DIAGNOSIS* LIVER NEOPLASMS/ 
RADIOTHERAPY* RADIOISOTOPE SCANNING* RADIOISOTOPES/ THERAPEUTIC 
USE* REVIEW (4) 



ACKERMAN NB 

CLINICAL AND EXPERIMENTAL USES OF RADIOISOTOPES IN TH E DIAGNOSIS Qir 
CANCER* 

AHER J SURG 1151633-6* MAY 66 

BONE NEOPLASMS/ DIAGNOSIS, BRAIN NEOPLASMS/ DIAGNOSIS* CALCIUM 
ISOTOPES* CESIUM ISOTOPES* DnA/ METABOLISM* EYE NEOPLASMS/ 
DIAGNOSIS* FLUORINE* GALLIUM* HUMAN (4)* IODINE ISOTOPES* 

"~ ibO (H5 

PKOiNTAL LObc 



DKAi^t Co, PFALZNER PK, LINELL EA 

INTRACAVITARY IRRADIATION OF MALIGNANT 
bRA 1 N TUM&URS, 

J NEURCdUKo 20:420-34* NAY 63 

AOOLEbCt^Cc* *ASTROCYTGKA, #t>RAlN 
Nc.OPL.ASnb , ftCESIUM ISGTCt-ES* #l>jkA MATER* 
COimTIwuEL- 

national library of medicine (medlars) 

Figure 33 



DIAGNOSTIC* LIVER NEOPLASM; 
•NEOPLASMS/ DIAGNOSIS* PHOi 
SCANNING* RUBIDIUM* SELEN' 
NEOPLASMS/ DIAGNOSIS 



ADAMS DD* KENNEDY TH* PURVE! 
COMPARISON OF THE THYROID. S' 
THYROTOXIC AND EUTHYROID PE( 




41 



LITERATURE SEARCHES 



A demand search is usually conducted for an individual and is 
therefore tailored to the unique information requirements of 
this person. Sometimes, however, a demand search is conducted on 
a topic of potentially wide interest (e.g., cardiac resuscitation, 
heart transplantation). Such a search may be selected for further 
processing in order that it may be widely distributed. The search 
then becomes known as a Literature Search. It is subjected to 
editorial procedures and photocomposed . 

As new titles become available, they are announced through notices 
in the following publications: NLM News , Index Med icus , Monthly 
Bibliography of Medical Reviews , Journal of the American Medical 
Assoc iation , Journal of the American Dental Association , Drug 
Research Reports , and Public Health Reports . An up-to-date list of 
titles, as well as copies of individual bibliographies may be 
requested without charge from the Literature Search Program, 
Reference Services, National Library of Medicine. 



42 



RECURRING BIBLIOGRAPHIES 



A further product from the MEDLARS data base is the series of 
recurring bibliographies. A recurring bibliography is a 
periodically published bibliography in a restricted subject 
area of biomedicine . A complete list of the bibliographies current 
produced is included in Appendix C. 

A recurring bibliography is produced in much the same way as a 
demand search. A search strategy is prepared to retrieve all 
citations relevant to the scope of a particular publication. 
For example, to produce the Index to Dental Literature a 
comprehensive strategy is designed to retrieve all citations 
of dental interest, whether from dental or general medical 
journals. However, the strategy developed to produce a 
recurring bibliography is extremely complex, involving the 
use of many different index terms in many different combinations. 
Most recurring bibliographies are developed as a joint venture 
between the National Library of Medicine and a professional 
medical organization. For example, the Index of Rheumatology 
is produced for the American Rheumatism Association Section 
of the Arthritis Foundation. The professional medical organ- 
izations involved designate subject experts to work with 
trained search analysts on the staff of the Library, in the 
development of an appropriate searching strategy. Usually, 
a strategy for a recurring bibliography will go through a 
number of iterations before it is finally accepted as a 
suitable formulation to produce the publication concerned. It 
will be subject to further continuous modification to ensure 
that it remains optimally responsive to the needs of the 
specialized audience it is to serve. 

The search strategy for a recurring bibliography is matched 
(monthly, bi-monthly, or quarterly, as appropriate) against all 
the citations input to MEDLARS since the last issue of that 
bibliography was produced. The magnetic tape of retrieved 
citations is sorted, formatted, and photocomposed by procedures 
similar to those used in the production of Index Medicus . The 
positive camera-ready copy thus created is then delivered to the 
professional organization sponsoring the bibliography. That 
organization is responsible for publication and distribution. 
Figure 34 is a specimen page from one recurring bibliography, 
the Index of Rheumatology . 



43 



INDEX OF RHEUMATOLOGY 



a monthly published by 

American Rheumatism Association Section 

of The Arthritis Foundation 
1212 Avenue of the Americas, New York, N.Y. 10036 
in cooperation with The National Library of Medicine 
Bethesda, Maryland 20014 



Vol. 5, No. 3 



March 1969 



A( ETABl I I M 



ARACHNODACTYLY 



Complete replacement arthroplasty of th< 
ring prosthesis Ring PA 
J bill Join, -ur, [Brtll 50 710 31. 
O.teomeir, of the ege runm n the pelv 



ACHILLES TENDON 



o endolholloels. studied by 
>n microscopy Chapman 
Rep Biol Med M 297 J0I 



hip by the Metaehr 



Lanrel I 533 4 6 Mar 69 
|3 cases of Marfan'! ayndromel Yoahlmura M 

Orlbop Sarg (Tokyo) 19 733-9. Aug 88 (Jap) 
[Dissecting aneurysm tn Marfan'a ayndrome] Apt Mia. 



chronic polyarthrlllal Klein c. 

Z Rheymaforach 27:433-7. Dec 86 (Ger) 
I The pltulury adrenal ails and psoriasis Metoplr 
In the trea 



al KUn Med (Mo 
[On Marfan'a syndroi 
Klin Med (Moskva) 
(A case of Marfan'a dli 
Klin Med (Moskva) 
(On Marfan 



AI.KAPTONI RIA 



Med 30 59-84. Dec 67 

■tad 



ikvat 45 78 11. Feb 67 (Run 
ie| Oanovlch BZ. 

45 125 9. Feb 87 (Ras) 
sese] Voloahchanko NZ. at al 

46 135 40. Au( 86 (Raa) 
i| Mallnovakll NN. at al. 



[Marfan 
Mamiuova SI. al al 
Zb Ncvropat Pslkhlat Koraako 

ARTHRITIS 



68 1521 4. 1968 (Rut) 



ALLERc. 

The role of the thymus In the pathofeneala of 
adjuvant Induced polyarthrttla In rats. Rylewaka A. at 
al Arcb laaaaan Tker Bap 16 747 58. 1*88 

[Clinical lectures and pathogeneals of nacrotlilnf 
aclerltlal Wollenaak J 

Kiln Mtl Aegenbellk 153 773 88. 1988 (Ger) 
[Some ref ularltlea and principles or clinical evaluation 
of blood ayatam change. In cardiovascular diseases 1 
Krylov AA Kardloloflla 6 *8 95. Oct 88 (Baal 



Maaalaa vaccina raactlona In a virgin populall 
FL. at al Aaaer J Epldem 69 168 75 

Typhoid fever In African 
Durban Scrag* 



Black 
. Fab 89 
nd Indian children In 



AMYLOIDOSIS 



. ..18 28, Feb 69 (108 ref I 
Psittacosis lymphogranuloma polyarthritis of aheap In 
Irueenaland. Tammemagl L. at al. 
Aaal Vel J 44 585 Dac 68 
Generallied pustular psoriasis. A clinical and 
epidemiological atudy of 104 cases Baker H, at al. 
Brit J Derm 60 771 93. Dac 68 
Waat of England and Walae dermatolog leal society. 



Kur 



I Usefulness of the Congo red teat In clinical practlc 
new method) Papa C. at al. 
Policlinic. | Prat I 74 1445 53. 13 Oct 87 ( 



_ Derm 60:839-40, Dac - 
bllng relapsing polychondritis In 



patient with ulcerative colitis Rosen SW. a 
Gastroenterology 56:323 SO. Feb 69 



ANKLE JOINT 



Wilson AB 



Recant advances In above knee pr 

Jr Arm limb. It 1 17. Auti 

I Ligament lastly of anklel Ouellet R. al al. 

He Med Canada 97 661 1. Jul 68 (Fre> 
,'Rsaectlon snd srthrodesls In s case of pigmented 

villi nodular synovitis or the snkle Joint) 

Zwlenchow.kl H 

Cblr Nartad Rorha Orlop Pol 33 779 83. 19*8 (Poll 

ANKYLOSIS 

R WHk*' n ° ,r *HA' C c0,r, '*" on * '" « rv "»l spondylosis 

Asner J Roentgen 103 370 4. Feb 69 
Hlstopalhology of otosclerosis Nagar GT 

Arcb Otolaryng (Chicago) 69 34 1 81, Feb 69 
A drilling Jig for arthrodeets of the hip. Caaa CA et al 

J Bone Joint Sarg [Brit I 51 115 9. 1 Feb 69 
Mould arthroplasty or the knee A tan year follow up 

study Piatt G. al al. 

> Bone Joint Bar* [Brill 51 78-67. 1 Feb 69 
-surgical treatment of massive bony ankylosis of the 

lemporomandlbular Joint Bromberg BE. at al 

Plaat Recomur Sarg 43 *0-70. Jan 66 
[Subacute Infantile polyarthrttla] Moulconaccl P 

Acquis Med Recent 69-95. 1987 (pre) 
[Osseous snkylosls of the s tapes snd Menler's 

syndrome) Martin H. et al 

J Franc Otorhlnolary ng 17 515 passim, Jun 6* (Pre) 
'H'.'."" 1 . " n ' n """ •• adjuvant of balneotherapy) 

Puffer E Wlrn Med Wacbr 1 16 8J7 40. 5 Oct 68 (Oer) 
[On fracturee In ankylosis] Pollono F. al al 

Minerva Ortop 16 158 61 Mar «7 (| U ) 
[Dirncultles In placing In the cllnlco-nosogrsphlc 

scheme an exceptional form of destructive 

osteo proliferating generallied ankylosing 

arthropathy] Lucherlnl T 

Reamatlsmo 19 61 80, Mar Apr 67 (Ha) 
[Effect of an aokylosed coiofemoral Joint on tha 
contralateral joint) Naiarova RD 
Prokl Takerk 46 33 8. 19*6 (Btul) 



Ion of geriatric patlanta for carpal tunnel 
syndrome raaulta of surgical therapy. Stern FH 
J Arner Oerlal Sot 17:113 5, Feb 69 
A drilling jig for arthrodaals of tha hip. Cass CA. al al. 

J Bone Joint Surg [Brill 51 135 9. 1 Feb 69 
Posterior dislocation and fracture dislocation of the 
hip A review of fifty seven patients. Hunter GA 
J Bone Joint Surg I Brit I 51:38 44. I Feb 69 
Arthritis -a clinical diagnosis. Sales LM. 
J Florida Med Ass 56:91-4, Fab 89 
Activities, events and outcomea In ambulatory patient 
care. Lawls CE. et al. 
New Eng J Med 280 *45 9. 20 Mar 69 
Rubella vaccination In adult females. Walbel RE at al 

New Eng J Med 2*0 682-5. 27 Mar *9 
Urinary glycollplda In Fabry's dlsaasa. Their 
examination In the detection of atypical variants and 
the pre symptomatic state Phlllppart M et al 
Pediatrics 43 201 6. Feb 69 
Crystal Induced arthritis Phelps P et al 

Postgrad Med 43 87-93. Jan 69 
The pseudo Hurler syndrome. Turner B 

Proc Aust Ass Neurol 5:145-7. 19*8 
Palindromic rheumatism case report with response to 
tndomethacln. Weaver AL. at al 
Southern Med J 62 1*1-4, Feb 69 
[ Acuta purulent arthritis of the hip In Infants Current 
diagnostic and therapeutic problems) Rlgsult P et si 
Ann Cblr Infant 9 145 56, Jul-Sep ** '(Pre) 
(Indications for surgical treatment of coiarthrltlal 
Mourgues G de Lyon Chlr «l:473-«. May 67 (Frei 
[Indomethacln. Clinical and biologic study conducted 
with 73 patlenta) Germain G. et al 
Un Med Canada 96:637-40, Jul 67 (pre) 
(Juvenile ankylosing ipondylltle] Schilling F et al 
Deotaeh Med Wsebr 94 473-6 passim. 7 Mar 69 (Oer) 
k r V" """"""^ determination of plasm, 
proteins by Immunopreclplutlon) Backer W at al 
Z KUn Chen, 8:111-11, May 66 ' t 0 „\ 

(Studies on the metabolism of trace elem.nts In 

v " u< " "" «">■"• Hw. 
cadmium chromium, molybdenum, manganese] 
Marti DP. at .1. z Klin Chsm 6 1714. May 68 (oir> 
[ Demonstration of tlaaue autoantibodies In progressive 



»7.00 (for.,,,,). For A. R. 



-eatment of psoriasis and psoriatic arthrltla) 

Med Lombard 22 Suppl 2917 28, 19*7 (ita) 

I Preliminary obaervatlona on the uae of cephalorldlne 
In certain skeletal affections) Lai G. 
Minerva Ortop 18:190-6. Mar 67 ,i,, 
; Difficulties In placing In the cllnlco-noaographlc 
acheme an exceptional form of deatructlve 
osteo proliferating generallied ankylosing 
arthropathy] Lucherlnl T. 

Reamatlsmo 19:61-80. Mar-Apr 67 ,na 
(Study on experimental osteomyelitis caused by 

Staphylococcus aureus, with special reference to lu 

pathology and the proceaa of bacterial proliferation! 

Hayashl I J Jap Ortbop Asa 42:935-48. Oct 88 u.p, 
[Complement and rheumatoid factor activity of the 

synovial fluid and Immunoelectrophoresis] Aba M 

Jap J CUa Path 16:677 81. Sap SS (Jap> 
[ Lipid metabolism In kidney diseases] Yoshltoshl Y et 

SI N.Iks 11:81410. Oct 88 ( 59 ref.) (J.p, 
I On the clinical aspects of so-called palindromic 

rheumatism (Intermittent angioneurotic 

arthropathy)) Gavrlkov na. et al 

Kiln Med (Moskva) 46 91 «, Aug 68 (Ras) 
(Ultrasonics In complex treatment of patients wltn 

tuberculosis] Eremlcheva Tl 

Probl Tuberk 45:44-9. 1987 , R „. 

(Role of tubercular ostitis and vascular change, 
connected with It In the development of arthrosis 
deformans (experimental study)] Nakonechnyf CD 
Probl Tuberk 46:74-80. IM8 (Has) 

[Effect of an ankylosed coxofemoral Joint on the 
contralateral joint) Naiarova RD. 
Probl Takerk 46:15-8. 19*8 (R u , 

ARTHRITIS, INFECTIOUS 

Acute suppurative arthrltla In children. Gustllo RB et 

al. Mien Med 52 219-25. Feb 89 
Glucose galactose malabsorption complicated by 

monlllal arthritis. Prultt AW et al 

Pediatrics 48:108-10, Jan •( 
The diagnosis and treatment of acute Infections of the 

hand Shamblln WR Southern Med J 62 209 12 Feb 69 
I Arthritis gonorrhoea). Report of a case In pregnancy 

with negative GR In serum and positive GR In the 

synovial fluid 1 Nielsen A. 

llge.kr Laeg 110:1667 6. 31 Oct 68 (Dam 
[Suppurated arthritis of the hip after cortisone 
Injections. Therapeutic Indications] Schnepp J et .1 
Lyon Chlr 63 422-4. May 67 '(Pre) 
I Preliminary observations on the use of cephalorldlne 
In certain skeletal affectlona] Lai G 
Minerva Ortop 18:190-6, Mar 67 (|ta) 
[ The Indications and contraindication, to tonsillectomy 
In children) Volovlk AB. 

Pedl.trll. 12:63-5. Nov 67 ,„„,, 

ARTHRITIS, JUVENILE 
RHEUMATOID 

Acute suppurative arthritis In children. Guatllo RB el 

al Mian Med 52 219-25. Feb 89 
[Subacute Infantile polyarthrlllal Moulconaccl P 

Acquis Med Recent 89-95, 1887 (Pre) 
(Juvenile ankylosing spondylitis] Schilling F et al 

Deutsch Med Wscbr 94:471-6 passim. 7 Mar 69 (Oer) 
1 Co""''""""" <° Ilia serolofy of juvenile polyarthritis) 

fehr K, el al Z Rheumaforaeh 27 399-410 Dec 88 (Oer) 
(Contribution to the knowledge of a new microscopic 

finding In the synovial fluid: 

neutrophll-phagocytoslng macrophages] Marmont A 

Minerva Med 59:5705-9. 22 Dec 66 (| U I 
[Rheumatic disease and rheumatoid diseases In 

children Dlfferencea In comparison with adulu Old 

concepts and recent acquisitions] Bulfarolll ». 

Minerva Pedlal 19 426-36. 10 Mar 67 (| U ) 
(AtUlnuclear antlbodlea, •ntlperlnuciear factor and 



> Tha Arthritis Foundation. 



Figure 34 



44 



SUITABILITY OF REQUESTS FOR PROCESSING 
AS MEDLARS DEMAND SEARCHES 



There are, of course, some restrictions on the use of the 
demand search service, as well as on various types of information 
which MEDLARS is not designed to provide. It is important that 
you recognize these restrictions; we therefore ask that you 
not request : 

1. Searches of the total MEDLARS file. Although the data base 
dates back to mid- 1963, experience has shown that most 
MEDLARS users are satisfied with a search of the more 
recent segment of the file. The Library, therefore, began 
limiting routine searches of the MEDLARS file to a period 
of 2k - 3% years. Requests for searches of the earlier 
files will be considered after you have reviewed and 
evaluated a search of the more recent ones, and sent us 
a completed appraisal form (enclosed with your bibliography) 
indicating why it is necessary to have the earlier material. 
For references to articles published before mid-1963, consult 
earlier volumes of Cumulated Index Medicus and Current List 
of Medical Literature. 



2. Author searches. The MEDLARS system is not designed to 
search on authors' names. Author indexes are available in 
Index Medicus and Cumulated Index Medicus . Authors ' addresses 
are not provided, but can frequently be located in directories. 



3. Verification of specific citations. This information is 
readily available in Index Medicus and elsewhere. 

4. Citations on a single subject, or concepts which may be easily 
coordinated, e.g., bladder neoplasms, cardiovascular com- 
plications in pregnancy. These citations may be found readily 
in Index Medicus under the appropriate headings (BLADDER 
NEOPLASMS; PREGNANCY COMPLICATIONS, CARDIOVASCULAR). 

5. Data or factual information. Standard handbooks, encyclopedias, 
and monographs should be consulted for specific data or facts. 

6. Subject matter not in scope of Index Medicus . Requests on 
subjects such as animal husbandry or general computer program- 
ming should be directed to specialized indexes ( Bibliogr aphy of 
Agriculture, Computer Abstracts ). For references to proceedings 
of congresses, symposia, and similar materials, as well as 
monographs and serials, consult the National L ibrary of Medicine 
Current Catalog , published monthly with quarterly and annual 
cumulations . 



45 



7. Translations of articles. Local librarians should be consulted 
for sources of translations or names of translators. 

To clarify the types of request that are suitable for processing as 
MEDLARS demand searches, and the types that are not, and also to 
illustrate some other reference tools that should be considered 
in conducting biomedically related searches, it is worthwhile to 
examine some typical subject requests. Twelve such requests are 
analyzed below. 

1. Pathogenesis, Diagnosis, and Treatment of Hydrocephalus. 

This request is not particularly appropriate for a machine search 
in MEDLARS. It asks for literature on hydrocephalus from virtually 
every viewpoint. To be complete, therefore, the search would have 
to be conducted on the single term HYDROCEPHALUS. 

Because no coordination of terms is necessary, the search can be 
done more economically by the requester himself, looking under 
the term HYDROCEPHALUS and its subheadings in Index Medicus and the 
Cumulated Index Medicus . However, perhaps the requester is 
interested in every possible reference to hydrocephalus, even 
if the reference is very slight. In this case a MEDLARS search 
may be justified. The printed indexes allow retrieval of only 
those articles in which hydrocephalus is treated centrally and for 
which the indexer has indicated that the term HYDROCEPHALUS should 
be a print ( Index Medicus ) term. 

A MEDLARS search will retrieve these articles plus others that 
discuss hydrocephalus in a more peripheral way, for which the indexer 
has assigned the term HYDROCEPHALUS as a non- print term. For the 
requester who needs these citations of minor relevance to hydrocephalus, 
it is possible to supplement the manual search in Index Medicus by 
a machine search conducted on HYDROCEPHALUS only as a non- print term. 

2. The Clinical Significance of the Third and Fourth Heart Sounds. 

Theoretically this question should be within the capabilities of 
MEDLARS. However, it cannot be handled well because the specific 
terms for the third and fourth heart sounds are not available in the 
MeSH vocabulary at the present time. The most specific term 
available is HEART AUSCULTATION. Obviously, the great majority 
of the articles indexed with this term would not be relevant to the 
specific topics sought by the requester. In this case, then, a 
better source than MEDLARS or Index Medicus would be a more spec- 
ialized bibliography related to the subject of cardiology and/or 
heart disease. For example, we can consult the subject index to 
Excerpta Medica, Section 18, Cardiovascular Diseases, and find 
specific subject headings for the individual heart sounds. These 
subject headings would then lead you to abstracts that deal exactly 
with the subject requested. 



46 



3. The Relationship between Blood and Cerebrospinal Fluid 
Oxygen Concentrations or Partial Pressures 

This is a request that is very appropriate for MEDLARS searching. 
It has three facets: the oxygen facet, the CSF facet, and the 
blood facet. A request involving a complex relationship such as 
this is very difficult to handle by means of a search in a con- 
ventional printed bibliography. In MEDLARS, however, we are able to 
look for the co-occurrence of three concepts rather easily. By 
searching on a coordination of blood terms, oxygen terms, and CSF 
terms, we are able to retrieve relevant citations like the one 
below : 

Dunkin RS , Bondurant S 

The determinants of cerebrospinal fluid P02. The effects 
of oxygen and carbon dioxide breathing in patients with 
chronic lung disease. 

Ann Intern Med 64: 71-80, Jan 66 

*Anoxia, Blood Gas Analysis , ^Carbon D ioxide/pharmacology , 
^Cerebrospinal Fluid, ^Cerebrovascular Circulation, Human 
(4), Hypercapnia (3), *Lung Diseases/complications , *0xygen, 
*0xygen Inhalation Therapy, Respiratory Function Tests 

4. Asherman's Syndrome of Intrauterine Synechiae 

It is possible to conduct a successful search in MEDLARS on this 
topic even though the MeSH vocabulary does not specifically include 
the subject headings ASHERMAN'S SYNDROME or INTRAUTERINE SYNECHIAE. 
We can approach it in other ways: by the use of the term ADHESIONS 
coordinated with the term UTERINE DISEASES or with subject headings for 
the specific conditions that make up the syndrome -- menstrual disorders, 
abortion, secondary sterility. 

Another good source of articles on this topic is the Science Citation 
Index. This published index lists current scientific papers under 
the papers that they cite. Thus, if we know where Asherman's 
syndrome was first described, we may be able to locate later papers 
that cite the original paper and thus have a high probability of 
being relevant to the subject sought. 

This syndrome was first described by J. G. Asherman in Journal of 
Obstetrics and Gynaecology of the British Commonwealth , 1948. When 
we check on this citation in Science Citation Index for, say, 1966, 
we find that Asherman's paper was cited in 1966 by J. R. Postle and by 
W. J. Sweeney. Full bibliographic references are given for these papers 
which, because they cite Asherman's original paper, have a high probability 
of being relevant to the subject of Asherman's syndrome. 



47 



5. Nerve Tissue Culture As Affected by Electrical Stimulation, 
Local Anesthetics, Ganglionic Blocking Agents, and Hypnotics 

This is another good MEDLARS search. The subject has wide 
ramifications and it would be extremely difficult to cover it 
comprehensively by conventional manual searching. However, it is 
susceptible to machine search in MEDLARS by coordination of nervous 
system terms and tissue culture terms and terms for the specific 
aspects being studied. For each of these facets there are very 
many different terms in MeSH . These can be searched and coordinated 
very efficiently by machine. Such a complex search would be very 
difficult to conduct manually. 

6. Potassium Levels in Milk and Milk Products 

Processing of this search through MEDLARS would retrieve some 
citations of interest, but the bibliography produced would not be 
truly representative of the subject because the journals indexed for 
MEDLARS cover this subject primarily in relation to human or animal 
nutrition. A more productive source for this request would probably 
be Chemical Abstracts , which covers a greater number of journals 
more directly related to this subject. Because this request has 
strong agricultural implications, another appropriate source to 
check would be the Bibliography of Agriculture , published by the 
National Agricultural Library. 



7. Skin Grafts in Monkeys 



This is a very good candidate for a MEDLARS search because it is 
very difficult to search for experimental animals in a conventional 
printed bibliography. Terms for experimental animals are usually 
not entry points in published bibliographies, and the user would thus 
have to rely entirely on the mention of the animal in the title of 
the article in order to identify pertinent references. This is true 
also for Index Med icus . Although experimental animals mentioned in an 
article are always indexed, these terms are rarely made print terms, 
so that the articles do not appear under the name of the animal in 
the printed index. However, these entries do appear as searchable 
terms on the magnetic tape files. Thus, through a MEDLARS search, 
we can coordinate SKIN/ trans plantation and MONKEYS and thus achieve a 
satisfactory retrieval that would not be possible by manual means. 

8. Chromosomal Aberrations in Humans, Animals, and Plants 

In this case a MEDLARS search could produce results on chromosomal 
aberrations in humans and animals but would retrieve little, if 
anything, on the plant aspect. Possibly the best source for this 
request would be Biological Abstracts , using the terms CHROMOSOME 
and CHROMOSOMAL as entry points to the permuted subject index 
Biological Abstracts Subjects In Context (BASIC) . 



48 



9. Medicine and Medical Care in Massachusetts 



MEDLARS is well equipped to handle this search because indexers are 
required to use geographic subject headings in indexing articles 
about a particular place. A machine search can be conducted on these 
geographic terms, whereas they are difficult to search on in conventional 
printed indexes, including Index Medicus . Such articles would be 
retrievable on a manual search only if the geographic name happened 
to be mentioned in the title of the article. 

10. Use of the Bender-Ges talt Test in Screening for 
Maladjustment 

A good response to this request can be obtained through MEDLARS, 
which uses BENDER- GESTALT TEST as a subject headings and also has 
many terms for psychological conditions and psychiatric disturbances. 
Journal coverage in MEDLARS is good in this area, with over 100 
journals indexed in psychiatry and another 60 or so in psychology. 
Another obvious source for this request would be Psychological Abstracts . 

11. Pneumoencephalography, Angiography, Electroencephalography, 
Echoencephalography , or Brain Scanning in Children Up to Four 
Years of Age 

Several factors make this request well-suited for a MEDLARS search. 
Age groups are routinely identified and indexed whenever an author 
indicates the ages of his patients in an article. It is difficult 
or impossible to search on age groups in printed bibliographies. Only 
in those rare cases when the author has indicated the age of his 
patients in the title of his report could such articles be retrieved. 
The large number of other factors in this question, the radiographic 
and electrodiagnostic techniques, are also well suited to MEDLARS, and 
the coordination of these terms with the age group term can be done 
easily and effectively. 

12. Spec trochemical Methods for the Determination of Calcium 

Any MEDLARS retrieval on this subject would be restricted to calcium 
in biological systems, whereas that may not be the intent of the 
request. A better source would be Chemical Abstracts , which is not 
limited to biological determinations but covers determinations of 
calcium wherever it occurs. 



49 



In the above examples, we have attempted to give some indication of 
the types of request that are suitable for machine search in MEDLARS 
and the types that are less suitable. We have illustrated the use 
of certain other sources that are appropriate to search for various 
types of biomedically-related requests. Only the major general 
tools have been mentioned. There are many other specialized 
bibliographies appropriate to specific subject requests, for example: 
International Pharmaceutical Abstracts , Arthritis and Rheumatic Diseases 
Abs trac ts , Abstracts of Hygiene , and Tropical Diseases Bulletin . 

You should also remember that MEDLARS is largely restricted to coverage 
of the journal literature. There is also much technical report 
literature dealing with biomedical subjects, and published indexes 
are available to locate these reports. For example, space medicine 
is well covered in Aerospace Medicine and Biology , while biological 
effects of radiation is well covered in Nuclear Science Abstracts. 



50 



FACTORS AFFECTING PERFORMANCE IN MEDLARS 



A computer-based retrieval system does not "deliver the answers" at the 
push of a button. The success or failure of MEDLARS, or any other 
information retrieval system, is dependent less on machine capabilities 
than on intellectual effort. This intellectual effort is exerted 
by the indexers, the search analysts, the vocabulary specialists 
and - very importantly - by the user himself. Generally speaking, the 
more effort the requester is willing to put into the use of MEDLARS, 
the better the result is likely to be. 

It is important to recognize that, for a particular request, the 
great majority of articles in the data base will not be relevant. 
Assume a MEDLARS data base of one million citations. For a particular 
specific request there may be, say, 20 relevant articles in the entire 
file. In other words, there are 999,980 non-relevant articles. We 
must not expect the MEDLARS search to retrieve only 20 citations, 
all of them relevant. This is fantasy. 

A more realistic result would be a search that retrieved 25 citations, 
12 relevant and 13 not relevant (Table II). We can express this 
result quantitatively by means of some simple ratios. The search has 
retrieved 12 of the 20 relevant articles contained in the data base. 
We can therefore say that the recall ratio for the search is 12/20 
or 60%,. In retrieving these 12 relevant citations, we have also 
retrieved 13 citations that the requester judges to be irrelevant. 
Therefore, the precision ratio of the search is 12/25 or 48%. This 
particular search, then, has operated at 60% recall and 48% precision. 

Unfortunately, recall and precision tend to vary inversely. That is, 
if we create a broad strategy that ensures high recall, we will, at 
the same time, tend to be operating at a low precision. On the other 
hand, if we create a very tight or stringent strategy in order to 
achieve a high precision, we will tend to be operating at a low recall. 

Consider (Table III) the request for literature on renal amyloidosis 
as a complication of tuberculosis. As we know, this request has three 
facets: the kidney facet, the amyloidosis facet, and the tuberculosis 
facet. We can prepare a very tight strategy for this request by 
specifying that a citation will only be retrieved if it has been indexed 
under a kidney term and a term indicating amyloidosis and a term 
indicating tuberculosis. 

We can expect that this tight strategy will retrieve comparatively few 
citations and that these citations will mostly be relevant. For 
example, it may be that the search retrieves only 20 citations, of 
which 18 are relevant and two are not relevant. The precision ratio 
is therefore 18/20 or 90%. 



51 



However, the 18 relevant citations retrieved may represent only a 
fraction of the total of relevant citations in the system. Perhaps 
there are 40 relevant citations in the data base. This search has 
retrieved only 18/40 or 45% (i.e., the recall ratio of the search 
is 45%). 

Alternatively, we could relax the search requirements by formulating 
a broader strategy. We could specify that two terms only need 
co-occur to cause retrieval: either a kidney term and an amyloidosis 
term or an amyloidosis term and a tuberculosis term. Now we are 
likely to retrieve many more citations and in so doing we will pull 
out a greater proportion of the relevant literature. By broadening 
our search strategy we tend to compensate for the fact that all 
indexing is selective. Perhaps there are articles dealing in some 
way with "renal amyloidosis as a complication of tuberculosis" in which 
the kidney aspect has not been brought out in indexing. These would 
be retrieved on the combination of an amyloidosis term and a tuberculosis 
term only. 

This broader, more relaxed strategy will probably give us a high recall, 
perhaps retrieving 38 of the total of 40 relevant articles (i.e., a 
recall ratio of 38/40 or 95%). However, in broadening the strategy 
we will also be retrieving many irrelevant items (for example, articles 
discussing the co-occurrence of amyloidosis and tuberculosis but 
not renal amyloidosis). Perhaps the search now retrieves 180 
citations of which only 38 are relevant. Precision has now dropped 
to 38/180 or 21%. 

The above example, which is hypothetical, illustrates an important 
fact that we should be aware of in using an information retrieval 
system: the fact that recall and precision do tend to pull against 
one another. Broad searches achieve high recall but low precision, 
while highly specific searches achieve high precision but low recall. 



52 



TABLE II 



20 RELEVANT 
999,980 NOT RELEVANT 



FANTASY 



FACT 



20 

Retrieved 
All Relevant 



25 

Retrieved 

12 Relevant 
13 Not Relevant 



RECALL 

12/20 = 60% 



PRECISION 

12/25 = 48% 



TABLE III 

RENAL AMYLOIDOSIS AS A COMPLICATION OF TUBERCULOSIS 
(40 relevant articles) 



KIDNEY and AMYLOIDOSIS 
and TUBERCULOSIS 



20 

Retrieved 
18 

Relevant 



V 



RECALL 

18/40 = 45% 

PRECISION 

18/20 = 90% 



KIDNEY and AMYLOIDOSIS 
AMYLOIDOSIS 'And TUBERCULOSIS 



180 
Retrieved 

38 

Relevant 



RECALL 

38/40 = 95% 

PRECISION 

38/180 = 21% 



53 



In fact, we can show the average operating range of a retrieval 
system as a curve plotting recall against precision (Figure 35). 
By varying our searching strategies, we can range up and down this 
performance curve -- to give us high recall (but low precision), 
high precision (but low recall), or a compromise between these 
extremes . 

This phenomenon is exactly analogous to what happens when we conduct 
a conventional manual literature search in published bibliographic 
sources (Figure 36). If we look only under the most pertinent 
headings in only the most likely sources, we are going to find 
mostly relevant literature but not all of it (i.e., we achieve 
high precision but low recall). On the other hand, if we search 
under many possible related headings in many different sources, we 
are likely to retrieve much more of the relevant literature but 
we will have to wade through many irrelevant references at the 
same time. In this situation, we are getting high recall but low 
precision. The same principle applies to mechanized retrieval 
systerrs. 



100% 




x x 

X A 
XX 

X 



RECALL 50 



- x 



0 



100% 




Figure 35 



54 



MANUAL SEARCH 




HIGH PRECISION HIGH RECALL 

LOW RECALL LOW PRECISION 



Figure 36 

Factors Affecting Performance of a Search 

Although we spoke earlier of an operating performance curve for 

a retrieval system, this curve represents only an average performance 

range. In some searches (Figure 35), MEDLARS is able to achieve 

very good results (high recall and high precision) towards the 

top right-hand corner of the diagram. In other cases, hopefully 

less frequent, the results turn out rather worse and fall in the lower 

left-hand corner of the diagram (low recall and low precision). 

What, then, are the factors that determine whether or not a particular 
search will achieve satisfactory results? We can say quite definitely 
that the success or failure of a search is not dependent on the 
computer and the data processing capabilities of MEDLARS. The computer 
merely acts as a matching device. It matches the index terms assigned 
to articles against the combinations of index terms that have been 
used to describe requests (i.e., the search formulations). When a 
match occurs, a citation is retrieved. 



55 



The principal problems of information retrieval, and the factors 
that determine the success or failure of a search, are intellectual 
problems. These problems are largely linguistic problems of semantics 
and syntax. The specific components of the retrieval system that 
govern its performance are: 



i. 


the 


interaction between the requester and the system 


2. 


the 


complexity of the request, 


3. 


the 


indexing, 


4. 


the 


vocabulary, and 


5. 


the 


search strategies, 



User-System Interaction 

A very important factor governing the success or failure of a search is 
the quality of the request made to the system. A request is a 
description of an information need. The more accurately this 
description reflects the true requirements of the requester, the 
better the search is likely to be. Sometimes a user will make a 
request that is much more general than the precise topic upon which 
he needs information, as in the real example included as Figure 37. 
Under such conditions, he must expect a search containing much 
irrelevancy. 




REQUEST 

Cancer in the fetus or 
newborn infant 

INFORMATION NEED 

Relationship between terato- 
genesis and oncogenesis at 
the cellular level 



On other occasions, the reverse occurs (Figure 38). Here the 
requester actually asks for something more specific than the true area 
of his interest: fatty acids rather than lipids in general. In this 
situation, the requester is going to receive only part of the 
literature of interest to him. 



56 




FIGURE 38 



REQUEST 

Crossing of fatty acids 
through the placental barrier 



INFORMATION NEED 

Crossing of lipids through 
the placental barrier 



In yet other situations (Figure 39), the stated request may only 
partly overlap the information need. In this example, the request 
is partly more specific than the actual information requirement and 
partly more general. As a result, both recall and precision failures 
are likely to occur. 



For a search to be successful, then, it is obvious that the request 
statement must accurately represent what the requester is really 
seeking from the search. A poor request almost automatically dooms 
a search to failure. 

Complexity of Requests 

A second factor that affects the performance of a search is the sheer 
complexity of the request. Some requests are easy to handle because 
they involve few concepts in precise relationships. Consider the 
following two requests: 




REQUEST 

Homonymous hemianopsia in 
visual aphasia 



INFORMATION NEED 



Homonymous hemianopsia and 
other visual field defects 
in patients having aphasia 
as a result of a_ tumor or 
cerebrovascular accident 



FIGURE 39 



57 



1. Crystalline lens in vertebrates, excluding humans. 



2. Synthesis of virus specific proteins and nucleic acids 

formed during the replication of RNA viruses (specifically, 
vesicular stomatitis virus) in animal and bacterial cells. 

The former request is relatively simple and here we can reasonably 
expect to achieve both high recall and high precision. On the 
other hand, the second request is much more difficult, involving 
complex concepts in complex relationships. MEDLARS could achieve a 
high recall on this search, but probably only at the expense of a 
low precision. 

Indexing 

Indexing policies and procedures obviously exert a tremendous effect 
on the performance of the system. Indexers are human, and sometimes 
they make mistakes. The most common type of mistake is the omission 
of an important term. Such errors do occur on occasion. Another 
factor is that of indexing policy. Indexing is a selective process. 
Generally, we do not index everything in an article. We index only 
the more important topics or themes. Consider an article that 
discusses 10 related topics. If we index all 10 we are being 
exhaustive in our indexing. When we index everything exhaustively 
("in depth"), we have the ability to achieve a high recall: the 
article can be retrieved in response to a request that relates to 
any one of the 10 topics, as long as these have been indexed. If, 
on the other hand, a requester asks for literature on topic 8, and this 
particular aspect has not been covered in the indexing, the article 
will not be retrieved. 

However, when we do index very exhaustively, we inevitably tend to 
be indexing some very minor aspects of articles. Consequently, articles 
are retrieved in response to requests for which they contain very 
little information and are judged to be irrelevant to the request. 
Thus, exhaustive indexing (a large number of terms used) will lead to 
high recall but low precision. Selective indexing (i.e., indexing 
the most important topics only) will, on the other hand, tend to 
produce high precision but low recall. 

For certain requests, we find that we have not indexed exhaustively 
enough and therefore miss certain articles that the requester would 
like to see. For other requests, some of the indexing tends to be 
too exhaustive, and articles are retrieved which contain only very 
slight reference to the topic of the request. We attempt to compromise 
in our indexing by choosing what we feel is an optimum level for 
the majority of requests made to MEDLARS. 



58 



Vocabulary of the System 



The vocabulary of MEDLARS ( Medical Subject Headings and other 
components) will obviously exert a great influence on the performance 
of the system. There are really two major components of the voca- 
bulary : 

1. Medical Subject Headings . The terms that an indexer must 
use to describe the contents of the articles. 

2. Entry Vocabulary . This consists of references from 
medical terms that occur in the literature to the 
appropriate MeSH term or term combinations. 

Frequently, the vocabulary will allow us to express a particular 
concept quite specifically. When we come to search on this subject, 
we can retrieve the relevant citations with very little irrelevancy. 
Both recall and precision may be high under these conditions. 

In other instances, we cannot express a topic precisely but must 
use a more general term to describe it. For example, there is no 
specific term, or combination of terms, in the vocabulary to 
precisely express the genetic concept "equational division" (Figure 40). 
This topic is indexed under the more generic term MEIOSIS. This 
means that when we do a search on the specific topic, we can retrieve 
articles on "equational division," but only as part of the broader 
class MEIOSIS. 



Equational Division 
index under 
MEIOSIS 



FIGURE 40 

In other words, we are forced to retrieve all meiosis articles and 
many of these will be irrelevant to the specific concept "equational 
division." The precision of a search on this subject is likely, 
therefore, to be very low. However, we have included the expression 
"equational division" in our entry vocabulary and are thus able to 
retrieve articles on this subject. If we did not include it in our 
entry vocabulary, different indexers might use different subject 
headings to describe it. Indexing inconsistency will result and the 
searcher may not search under all possible headings for literature 
on this precise topic. Recall failures will therefore occur. 




59 



Other search failures are caused by ambiguous or spurious relationships 
between terms. For example, suppose a requester is interested in 
literature on the co-occurrence of mongolism and leukemia in the 
same patient. This search is conducted on the combination: 

(any mongolism term) and (any leukemia term) 

This search retrieves some relevant articles, but, at the same time, 
brings out some irrelevancy. This is because it retrieves some 
articles that discuss a number of different patients, some of whom 
have mongolism and some leukemia, but these conditions do not co- 
exist in the same patient. This is a false coordination . The 
two terms that caused the retrieval are essentially unrelated in 
the retrieved article. 

A second type of failure, due to syntactical problems in the 
vocabulary, we can call an incorrect term relationship . This is 
the situation in which the two terms that caused retrieval are 
related in the retrieved article but not in the way that the requester 
wants them related. For example, a search is conducted on the 
subject of bovine leukosis. One term combination searched on is 
CATTLE and LEUKEMIA . Some of the articles retrieved do not deal 
with cattle leukosis but with the reaction of sera from human leukemia 
patients with bovine cell cultures. 

Searching Strategies 

The final factor governing success or failure of a MEDLARS search is 
the quality of the search strategy. As mentioned previously, a 
search can be made very general, in order to ensure high recall, 
or it can be made highly specific to achieve high precision. With a 
broad search, we are almost bound to have irrelevancy. With a 
highly specific search, we are almost sure to miss some of the 
literature. Quite often, the searcher will compromise by designing a 
strategy that will retrieve most of the relevant literature, but, 
at the same time, will operate at a tolerable precision. 

If we want to achieve high recall, it is important that the search 
analyst be comprehensive in his strategy. That is, he must cover 
all reasonable approaches to retrieval. Consider a search for 
literature on "oral manifestations of neutropenia." Neutropenia 
is covered by the MeSH term AGRANULOCYTOSIS. The search was 
conducted on the following strategy: 

AGRANULOCYTOSIS and ORAL MANIFESTATIONS 

or 

any anatomical term indicating the 
oral cavity (e.g., MOUTH, LIP, GINGIVA) 



60 



However, this strategy is not fully comprehensive because the 
searcher has not used any terms indicating specific oral manifestations 
(e.g., stomatitis). Therefore, some of the relevant literature was 
missed by this search. 



USING THE SYSTEM MOST EFFECTIVELY 



In the above discussion, we have attempted to illustrate the 
major factors governing the success or failure of a MEDLARS search. 
It is clear that these are not machine factors. Rather, they are 
intellectual problems relating to indexing, vocabulary control, 
searching strategies, and the quality of requests. 

What can you, the user, do in order to make the best possible use 
of MEDLARS? First and foremost, you must be prepared to put 
effort into making your exact needs known to the system. It is 
important that you exercise as much care as possible in completing 
the MEDLARS Search Request Form (see Appendix A). 

Section 9 of the form provides for a detailed statement of the 
subject matter on which you are requesting a search. Be as 
specific as possible and define any terms that may have special 
meaning in your request. Use your own terms in describing your 
need. Do not try at this point to phrase your request in terms 
selected from Medical Subject Headings . 

In Section 10, record the purpose for which the search is being 
conducted. Sometimes this helps to clarify a request statement that 
is otherwise obscure. For example, one requester asked for a 
search to be conducted on "body heat and body temperature as related 
to perspiration, water vapor, and inert gases." It was only when 
he indicated the context of his request — he was working on thermal 
comfort of astronauts in space cabin atmospheres -- that his request 
became more meaningful. 

Section 11 is extremely important. It provides check-off boxes to 
help you to limit the scope of your request, where such 
limitations are appropriate. For example, you may be interested 
only in humans or only in certain animals. You may be interested in 
a particular organ under normal conditions or only under patho- 
logical conditions. The form helps you to be more precise in making 
your needs known to the system. 

In Section 12, please record citations to any papers that you 

already know to be relevant to your request. These have a dual purpose 

First they give the searcher further help in understanding 

the exact area of your interests. Second, they can be used by the 

searcher after the search is conducted, to judge how successful 

the search has been. If you found some of these relevant papers 

in Tndex Medicus, it may be useful if you record the subject headings 

under which these citations were discovered. 



61 



Finally, in Section 13 of the form, you are asked to make an 
estimate of how many articles on the subject of your request you 
expect to have been published in the last three years. Also, you 
are asked to indicate whether you want the search to be broad, to 
ensure high recall, or narrow, to ensure high precision. As 
emphasized earlier, it is extremely important that your request 
accurately reflect your exact information requirements. The 
request form is designed to help you make these requirements known 
to us as clearly as possible. 

There is one more way in which you can help us to improve the 
performance of MEDLARS. When we send you the search results, we 
will enclose a search appraisal form. This is a short form 
(see Figure 41) designed to record your comments on the adequacy 
of the search. We ask you to be sure to complete and return this 
form. It is pre-stamped and pre-addressed . 

These appraisal forms allow us to identify searches that have 
produced poor results and help us to determine why. On the basis 
of this analysis, we are able to make improvements in our 
vocabulary, our indexing policies, and our searching methods. By 
these continuous quality control procedures, we can take any 
corrective action needed to keep MEDLARS responsive to the needs 
of the biomedical community. 



62 



MEDLARS CENTER: 
SEARCH ANALYST: 
REQUESTER: 
SEARCH NO,: 
DATE RELEASED: 



POSTAGE AND FEES PAID 
U.S. DEPARTMENT OF H.E.W. 



Quality Control Staff 
Bibliographic Services Division 
National Library of Medicine 
8600 Rockville Pike 
Bethesda, Maryland 20014 



FOLD ON OA:"iiD LINE 



FOLD ON DASHED LINE 



MEDLARS SEARCH APPRAISAL 



IT IS IMPORTANT THAT WE RECEIVE AN INDICATION OF HOW WELL THIS SEARCH HAS SATISFIED YOUR REQUIRE- 
MENTS. This will indicate system effectiveness and allow us to correct any failures. This continuous evaluation will 
enable us to provide users with the best possible search results. We urge ycu to please answer the following questions and 
return the form to us. It is pre-franked and pre-addres sed for your convenience. 



1. Your search printout contains citations. Please indicate approximately how many of the articles cited are: directly 

relevant , peripherally relevant . and, not relevant , to your information needs. 

2. Consider the articles that you judged not relevant. There are several possible reasons why an article may be "not relevant" (e.g., 
it relates to a topic outside the scope of your request or it deals with the required subject but from a viewpoint different from that 
requested.) Please give specific details as to why certain articles retrieved by this search are not relevant to your information 
needs: 



NIH- 1393-3 
REV. 9-69 



Figure 41 



63 



BUREAU BUDGET NO. 68R89I 
APPROVAL EXPIRES 6-71 



I Con 9 ,der the .rl.cle. Ih.t you judged relevant. How many of these were brought to your attention for the first time by this 
MEDLARS search' 



4. Of ..I the relevant arl.cle, that you know to have been publ.shed from January 1967 to date, this MEDLARS search retrieved: 

□ APPROXIMATELY 100% □ APPROXIMATELY 50% 

□ APPROXIMATELY 75% □ APPROXIMATELY 25% OR LESS 

Please g.ve citations for any relevant articles (publish tram January 1967 to date) that were not retrieved by this MEDLARS search: 
AUTHOR(S) TITLE OF ARTICLE JOURNAL DATE 



15) 



5. Was this search of material value (e.g., time or eltort saved, duplication avoided) to your investigation? 
If so, in what way was it of value? If not, why was it of no value? 



6. Having seen the results of this search, do you feel that the wording of your request clearly indicated the type of articles that you 
were looking for 3 If, in the light of the search results, you can now re-phrase your request more precisely, please do so. Please 
state items you are explicitly interested in as well as items in which you are not interested. 



7. Did you receive the citations in time to be of use? (Please check the appropriate box) 
Q YES or Q NO 



Thank you very much for helping us in the continuous monitoring of MEDLARS performance. 
NIH- 1393-3 " 

rev. 9-69 Figure 42 

0 1969-356-245 



64 



SUBMITTING REQUESTS 



When the request has been completed, send it to your regional medical 
library or nearest MEDLARS center. (See Appendix D) MEDLARS search 
requests sent directly to the National Library of Medicine will be 
referred to the appropriate MEDLARS center. 

There is no charge at present for the Demand Search Service at MEDLARS 
centers within the United States; however, we require that you complet 
a form appraising the bibliography you receive. 

A list of foreign MEDLARS centers is also found on Appendix D. Users 
in foreign countries receiving services through the Agency for Inter- 
national Development (AID) may send requests to the Head, MEDLARS 
Management Section, Bibliographic Services Division, National Library 
of Medicine, 8600 Rockville Pike, Bethesda, Maryland 20014. 

The processing time for a demand search from the time the request is 
received is approximately two to three weeks. 



65 



ACCESS TO ARTICLES CITED IN MEDLARS BIBLIOGRAPHIES 



The 2,300 journals indexed for MEDLARS are listed in the List of 
Journals Indexed published annually by the Library. Access to the 
original publications cited, to reprints, or to copies of articles may 
be had from the following sources: 

1. Reprints of articles are frequently available directly 
from the author or publisher. 

2. Medical libraries in local university medical centers, 
medical schools, health centers, hospitals, and state or 
county medical societies often have the material on hand, 
or by means of union lists know where it can be obtained 
through interlibrary loan. 

3. Special libraries or libraries of national associations in the 
various fields of medicine can provide much of the literature 
that is indexed. 

4. If your librarian cannot obtain the material through 
interlibrary loan elsewhere, the loan request may be 
directed to Regional Medical Libraries, such as the 
Francis A. Countway Library of Medicine in Boston, which 
accept requests from libraries in their Region. 

5. If there is no Regional Medical Library in your Region and 
the other sources have failed to produce the article cited, 
librarians are authorized to request the material from the 
National Library of Medicine, according to the NLM Interlibrary 
Loan Policy. 



66 



APPENDIX A 



NATIONAL LIBRARY OF MEDICINE 

MEDLARS MANAGEMENT SECTION 
8600 Rockville Pike 
Berhesda, Maryland 20014 




DATE 

3/4/69 

Is this your first request to MEDLARS? 


MEDLARS SEARCH REQUEST 




YES □NO 


1. INDIVIDUAL WHO WILL ACTUALLY USE THIS BIBLIOGRAPHY 
First Middle 


Last Name 


TELEPHONE NO. 



John 



Stuart 



Reynolds, Ph.D. 



301- 873-9322 



2. TITLE 

Assistant Professor of Environmental Health 



3. ORGANIZATION (Department, Bureau, Branch, Division, etc.) 

Department of Environmental Health 
School of Hygiene 


4. ORGANIZATION (University, Corporation, Company, etc.) 

Johns Hopkins University 


5. STREET ADDRESS AND CITY 

611 N. Wolfe Street Baltimore 


6. STATE AND ZJP CODE 

Maryland 21205 


7. REQUEST SUBMITTED BY (If ditterent from above) 

Mary Hartshorn, Librarian 


TELEPHONE NO. 

301- 873-5221 



8. SEARCH ANALYST (Leave Blank) 



The requester identification (items 1 through 7) should 
include your full name, degree, telephone number, 
position, organization, and full address. Please be 
certain to include your telephone number so the search 
analyst who handles your request may contact you if 
necessary. 



67 



ALL OF THE QUESTIONS THAT FOLLOW ARE DESIGNED TO PROVIDE INFORMATION NEEDED TO DE VE :LOP A B "Bf-'pCRAPHY 
THAT IS RESPONSIVE TO YOUR NEEDS. YOUR CARE IN PROVIDING FULL INFORMATION WILL AFFECT THE USEFULNESS OF 
THE CITATIONS THAT YOU WILL RECEIVE. 



9. DETAILED Statement OF REQUIREMENTS: Please describe, in your own words, the subject matter for which the search is to be 
conducted. Be as specific as possible. Define any terms that may have special meaning in your request. Also if thete are points 
NOT to be included, please state these. 

I apj interested in articles on the effects of atmospheric contamination on health, 
specifically studies on air contaminants such as hydrocarbons and other carcinogens. 

I am not particularly interested in smoking as it affects health, but articles on 
primary lung cancer in non-smokers are of interest to me. 



Under item 9 state your needs without being limited by any 
preconceived ideas about what MEDLARS can or cannot do 
for you. Do not attempt to translate your question into 
words that you feel may be easier for a non-specialist to 
understand, because you may distort your actual intention. 
It is the MEDLARS analyst's job to understand your request 
in your own terms. If necessary, he will call you for 
clarification. 

Please avoid the use of terms that are either more general 
or more specific than you really intend. Do not say aromatic 
hydrocarbons if you mean anthracenes; do not say aromatic 
hydrocarbons if you are interested in all hydrocarbons. 



68 



Page 2 of 3 



10. SEARCH PURPOSE: Please indicate the purpose for which this search will be used (e.g., preparation of a book, book chapter, 
journal article, or review article; for immediate clinical application; ongoing research; prospective research; grant application; 
paper presented at symposium, etc.). Give specific details that will put your request into context. 

I am writing a critical review on carcinogens as air pollutants. 



For item 10 you should state fully the purpose for which the 
search is being requested. This information places your 
request in the context of that purpose, and materially aids 
the MEDLARS analyst in preparing your search for pro- 
cessing. 



69 



II, SEARCH LIMITATIONS: Please check all boxes that are appropriate to the scope of your request. State your needs as specifically 
as possible, even though we may not be able to meet these precise needs in some cases. Your replies will allow the search 
analyst to design a strategy that, as far as possible, will avoid types of literature that are of no interest to you. 

(X) NO RESTRICTIONS |^] HUMAN SUBJECTS 

I 1 VETERINARY MEDICINE: If only certain animals or animal groups are of interest, please list these: 



animal EXPERIMENTS: If only certain animals or animal groups are of interest, please list these: 



lX]male 

f^T] FEMALE 



[~Xl NORMAL STATE 



[X ] DISEASED STATE 



| | CLI NICAL RESEARCH (testing ol drugs or technics 
in humans only) 



□ 



IN VITRO STUDIES 

(ol animal or human tissues or tluids only) 



| | CASE HISTORIES 



LANGUAGE RESTRICTIONS: 

[X] ACCEPT ALL LANGUAGES 

I I ACCEPT CERTAIN LANGUAGES ONLY (please specily) 



I | ACCEPT ONLY ENGLISH 



AGE GROUPS: If only certain age groups are of interest, please indicate which ones: 

Any age group 



GEOGRAPHIC RESTRICTIONS: If only certain regions are of interest, please list these: 

No geographic restrictions 



R is important that the limitations you desire be stated (item 11) 
There is no purpose in burdening you with experimental studies 
if you are interested only in the disease as it occurs naturally 
in humans or giving you citations to articles in Japanese or 
Russian when you read only English and French. 



70 



Page 3 of 3 



12. KNOWN RELEVANT PAPERS: Please carry out a preliminary literature search of your own before submitting this request PI 

MEDLARS, and supply full bibliographic citations below for relevant articles you have found. Wherever possible, they should be 
journal articles published since January 1966. These citations will be used as a guide in retrieving similar citations related to 
your needs. They will also be used in a later appraisal of the results of this search. If no relevant papers have been found, plea: 
state "none found". 

Anderson DO: The effects of air contamination on health. 3. 

a. Canad Med Ass J 97:802-6, 23 Sep 67 

Baird VC : Effects of atmospheric contamination on cancer mortality in 

b. petroleum refinery employees. 
J Occup Med 9:415-20, Aug 67 

Gross, P, DeTreville RT, Toker EB, et al: Experimental asbestosis. The 
c ' development of lung cancer in rats with pulmonary deposits of chrysotile 
asbestos dust. Arch Environ Health (Chicago) 15:343-55, Sep 67 

d. Clemo, GR: Some constituents of city smoke. 
Tetrahedron 23:2389-93, May 67 

e Abelson PH: Progress toward abatement of air pollution. 
Science 160:257, 19 Apr 68 

If you used INDEX MEDICUS for your preliminary search please list the subject headings under which you sought citations: 
AIR POLLUTION, CARCINOGENS, ASBESTOSIS, NEOPLASM STATISTICS 



We ask you to carry out a preliminary literature search in 
Index Medicus or other sources (item 12) before submitting 
your request. Providing citations pertinent to your request 
will enable the search analyst to understand your question 
better and will clarify the scope of your interests. It will 
assist the analyst if the reference is correctly cited and 
includes the full bibliographic data: author (s), journal 
title, volume number, date of issue and pagination. 



71 



IS. SEARCH REQUIREMENTS: Pl.o.e ch.ck en* el th* ben** b*lew to Indlcot* the typ* of eeoreh thot you would prefer! 

fcH A broad search designed to retrieve as many as possible of the relevant citations, but which 
might also retrieve many irrelevant citations. 

| | A narrow search designed to retrieve some only of the relevant citations, but with few 
accompanying irrelevant citations. 

NUMBER OF CITATIONS EXPECTED: PUa»* ch.elc th* opproprlot* box fo indlcot* th* number of journal article* deollng with the lubject of 
your request that you contldar likely to have been publi*h*d sine* January 1966. 

□ 0 CllO - SO O»01 -200 

Q 1 - 9 0081 -100 □ »» • 500 

I I OVER 500 



1*. PRINT ON: 



3" x 5" c*rd* or [^J 8 }" * 1 1 " paper 



NIH-1393-1 

(9-68) 



We need to know (item 13) whether you want as many relevant 
citations as possible at the expense of having to sift through a 
fair number of unwanted articles, or whether you prefer a 
bibliography having as few irrelevant citations as possible 
even if this means not retrieving some pertinent ones. 

As a result of your having performed a preliminary search of 
your own, you can probably estimate the number of pertinent 
articles likely to have been published since January 1966. 
Please give us this estimate by checking the appropriate box. 

Your bibliography can be printed on 3" x 5" cards or on 
continuous 8 1/2" x 11" computer paper (item 14). 



72 



APPENDIX B 



NATIONAL LIBRARY OF 

The following publications are available at the prices quoted 
from the Superintendent of Documents, U.S. Government Print- 
ing Office, Washington, D.C. 20402. 

CUMULATED INDEX MEDICUS 
Volume 10 (1969), is a cumulation in eight volumes of the 
approximately 224,000 citations to articles appearing in Index 
Medicus in 1969. Included, in addition to CIM Author and 
Subject Sections, are Medical Subject Headings, List of Journals 
Indexed in Index Medicus, and Bibliography of Medical Reviews. 
Price: $90.50 ($100.00 foreign). Volume 9 (1968) also avail- 
able; price: $72.25 ($80.55 foreign). 

MEDICAL SUBJECT HEADINGS, 1970 Edition 
The 1970 edition of Medical Subject Headings is published 
as Part 2 of the January 1970 issue of Index Medicus. The ap- 
proximately 7,400 subject headings in the 1970 MeSH are ar- 
ranged alphabetically, with cross references, and in categorized 
lists. Available separately, price: $3.00. 

LIST OF JOURNALS INDEXED IN INDEX MEDICUS 
The 1970 List of Journals Indexed contains four listings of 
journals indexed in Index Medicus: title, abbreviation, subject, 
and geographical. Price $1.25. 

ABRIDGED INDEX MEDICUS 
A monthly bibliography, based on articles from 100 
English-language journals, designed for the needs of the indi- 
vidual practitioner and libraries of small hospitals and clinics. 
To begin January 1970. Annual subscription price: $12.00 
($15.00 foreign); $1.00 for individual issues. 

INDEX MEDICUS 
Index Medicus is published monthly as a bibliographic 
listings of references to current articles from approximately 
2,300 of the world's biomedical journals. Each issue contains a 
subject and name section and a separate Bibliography of Medi- 
cal Reviews. Medical Subject Headings ($3.00) is included as 
Part 2 of the January issue. Price: $63.00 ($78.75 foreign); 
single issues $5.00. 

MONTHLY BIBLIOGRAPHY OF MEDICAL REVIEWS 
The Monthly BMR is a series designed to provide quick 
guidance to the latest reviews in the journal literature of bio- 
medicine. Each monthly issue duplicates the material appearing 
in the Bibliography of Medical Reviews section of the corre- 
sponding monthly issue of Index Medicus. Price for one year's 
subscription (twelve monthly issues): $4.50 ($5.75 foreign); 
single issues $0.40. 

NATIONAL MEDICAL 
AUDIOVISUAL CENTER CATALOG 
The 1968 NMAC Catalog lists audiovisuals available on 
short-term free loan to health professionals from NLM's 
Atlanta-based National Medical Audiovisual Center. National 
Institutes of Health Publication Number 451. 97 pages Price- 
$0.75. 

FILM REFERENCE GUIDE FOR 
MEDICINE AND ALLIED SCIENCES 
Published annually for the Federal Advisory Council on 
Medical Training Aids. The 1968 edition contains information 
on approximately 2,700 films. Public Health Service Publication 
Number 487, Revised 1968. 386 pages. Price: $2.75. Supple- 
ment, 1969. Price: $0.75. 



MEDICINE PUBLICATIONS 

NLM CURRENT CATALOG 
Bibliographic listing of citations to publications cataloged 
by the Library. Issued beginning January 1970 in three forms: 
(a) monthly (name section only), (b) quarterly (non-cumulat- 
ing, subject and name sections), and (c) annual cumulation 
(subject and name sections). Prices: (a) 12 monthly issues — 
$7.50 ($9.50 foreign); single issues, $0.65; (b) 4 three-month 
cumulations (quarterlies) — $13.00 ($16.25 foreign); single is- 
sues, $3.25; and (c) annual cumulation — $16.25 ($20.35 for- 
eign). [1969 Annual Cumulation (available March 1970), price: 
$14.25 ($17.85 foreign).] 

TOXICITY BIBLIOGRAPHY 
The quarterly Toxicity Bibliography covers the adverse and 
toxic effects of drugs and chemicals reported in the approxi- 
mately 2,300 journals indexed for Index Medicus. Price: $14.00 
per year ($17.50 foreign); single issues $3.50. 

NLM CLASSIFICATION 
The National Library of Medicine Classification: A Scheme 
for the Shelf Arrangement of Books in the Field of Medicine 
and Its Related Sciences. Third Edition, 1964, with 1969 Supple- 
mentary Pages. Public Health Service Publication Number 1108, 
Reprinted 1969. Price: $2.75 ($3.45 foreign). 

A CATALOG OF SIXTEENTH CENTURY PRINTED 
BOOKS IN THE NATIONAL LIBRARY OF MEDICINE 
Over 4,800 rare sixteenth century printed volumes from 
NLM's History of Medicine Division collection are listed. Some 
1,500 printers and publishers and 188 different printing centers 
in fourteen European countries are indexed in detail. Casebound. 
1967. 698 pages. Price: $5.25. 

INTERNATIONAL BIBLIOGRAPHY OF 
MEDICOLEGAL SERIALS 1736-1967 
An annotated listing of serials published on legal medicine 
and related fields. Includes six indexes (title, editors, publishers 
and sponsors, subject, geographical, and chronological). 1969. 
Price: $1.25. 

BIBLIOGRAPHY OF THE HISTORY OF MEDICINE 
Number 3, 1967, is the third of an annual series of bibli- 
ographies on the history of medicine and related sciences, pro- 
fessions, and institutions. Prices: Number 2, 1966 (Public 
Health Service Publication Number 1540-2) $1.25; Number 3, 
1967 (PHS Pub. No. 1540-3) $2.75. 

PRINTS RELATING TO DENTISTRY 
Includes reproductions of 67 prints illustrating the history 
of dentistry from the Library's extensive collection of pictures of 
nonclinical medical interest. Dates of the prints range from the 
15th to 20th centuries. Public Health Service Publication Num- 
ber 1605. 1967. 36 pages. Price: $0.50. 

MEDLARS: 1963-1967 
Comprehensive description of NLM's Computer system, 
MEDLARS (Medical Literature Analysis and Retrieval System). 
76 pages with illustrations. Public Health Service Publication No. 
1823. 1968. Price: $0.75 



GUIDE TO MEDLARS SERVICES 
Available without charge from NLM. Write to: Office of 
Public Information, National Library of Medicine, 8600 Rock- 
ville Pike, Bethesda, Maryland 20014. 



73 



APPENDIX C 



NATIONAL LIBRARY OF MEDICINE RECURRING BIBLIOGRAPHIES 



The National Library of Medicine, through its computer-based MEDLARS (Medical Literature Analysis and Retrieval System), periodi- 
cally produces lists of citations to journal articles in specialized biomedical fields. Most of these lists, termed "Recurring Bibliographies," 
are printed and distributed by nonprofit professional organizations and other government agencies with whom the Library cooperates. 



( 1 ) The Bibliography on Medical Education is published 
monthly in the Journal of Medical Education ($15 per year). 
Cumulations for 1964-65 and 1966 are available from the 
American Association of Medical Colleges, 2530 Ridge Avenue, 
Evanston, Illinois 60201, for $2.00 each. 

(2) The quarterly Cerebrovascular Bibliography is prepared 
under the auspices of the Joint Council Subcommittee on Cere- 
brovascular Disease, National Heart Institute, National In- 
stitutes of Health, Bethesda, Maryland 20014. Distribution is 
limited. For information write to the Executive Secretary, Joint 
Council Subcommittee on Cerebrovascular Disease. 

(3) The monthly bibliography, Fibrinolysis, Thrombolysis, 
and Blood Clotting, is distributed by the National Heart In- 
stitute. For information write to Dr. James M. Stengle, National 
Heart Institute, National Institutes of Health, Bethesda, Mary- 
land 20014. 

(4) The monthly Index of Rheumatology is available from 
the American Rheumatism Association Section of The Arthritis 
Foundation, 1212 Avenue of the Americas, New York, New 
York 10036. Price: $6 per year ($7 foreign); $3.50 to members 
of the American Rheumatism Association. 

(5) The quarterly Index to Dental Literature is sold by the 
American Dental Association, 211 East Chicago Avenue, 
Chicago, Illinois 60611. Price: $20 for four cumulative issues, 
(including annual cumulation); $10 for annual cumulation 
alone. 

(6) The quarterly International Nursing Index is sold by 
the American Journal of Nursing Company, 10 Columbus Circle, 
New York, New York 10019. Price: $15 for four cumulative 
issues (including annual cumulation); $12.50 for annual cum- 
ulations. 

(7) The quarterly Artificial Kidney Bibliography is pub- 
lished by the National Institute of Arthritis and Metabolic 
Diseases. For information write to the Scientific Communications 
Officer, National Institute of Arthritis and Metabolic Diseases, 
National Institutes of Health, Bethesda, Maryland 20014. The 
bibliography is sold by the Superintendent of Documents, U.S. 
Government Printing Office, Washington, D.C. 20402. Price: 
$1.00 per year ($1.25 foreign); single issues, $0.30. 

(8) The bimonthly Endocrinology Index is published by the 
National Institute of Arthritis and Metabolic Diseases, National 
Institutes of Health, Bethesda, Maryland 20014. The biblio- 
graphy is sold by the Superintendent of Document, U.S. Gov- 
ernment Printing Office, Washington, D.C. 20402. Price: $16 
per year ($20 foreign); single issues, $2.75 



(9) The Bibliography of Surgery of the Hand, a quarterly, 
is published and distributed by the American Society for Surgery 
of the Hand. For information write to John P. Adams, M.D., 
Chairman, American Society for Surgery of the Hand, 2150 
Pennsylvania Avenue, N.W., Washington, D.C. 20037. 

(10) The Anesthesiology Bibliography, a bimonthly, is 
published and distributed by the American Society of Anesthe- 
siologists. For information write: Wood Library, Museum of 
Anesthesiology, American Society of Anesthesiologists, 515 
Busse Highway, Park Ridge, Illinois 60068. 

(11) The quarterly Toxicity Bibliography is published by 
the National Library of Medicine and distributed by the Sup- 
erintendent of Document, U.S. Government Printing Office, 
Washington, D.C. 20402. Price: $14.00 per year ($17.50) 
foreign); single issues, $3.50. 

(12) The monthly Current Bibliography of Epidemiology 
(CuBE) is published by the American Public Health Associa- 
tion. For information write to the Editor, CuBE, American 
Public Health Association, 1740 Broadway, New York New 
York 10019. 

(13) The Neurosurgical Biblio-Index, a quarterly, is pub- 
lished by the American Association of Neurological Surgeons. 
For information write to the Subscription Manager, Journal of 
Neurosurgery, Suite 1230, 251 East Chicago Avenue, Chicago, 
Illinois 60611. 

(14) The Cranio-Facial — Cleft Palate Bibliography is pub- 
lished quarterly by the American Cleft Palate Association. For 
information write to the Chairman, Nomenclature Committee, 
Box 3098, Division of Plastic, Maxillofacial and Oral Surgery, 
Duke University Medical Center, Durham, North Carolina 
27706. 

(15) The Index of Investigative Dermatopathology and 
Dermatology is published monthly by the Universities Asso- 
ciated for Research and Education in Pathology, Inc. For in- 
formation write to the UAREP, 9650 Rockville Pike, Bethesda, 
Maryland 20014. 

(16) The Recurring Bibliography of Hypertension is pub- 
lished bimonthly by the American Heart Association, Inc. For 
subscription information write: The American Heart Association, 
Inc., 44 East 23rd Street, New York, New York 10010. 



74 



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U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE 
Public Health Service 
National Institutes of Health